# Accordion

Show and hide sections of content from their headings.

Use an Accordion for content people can explore one section at a time, such as answers, settings, or a course outline. Each heading is a button that opens its panel.

```vue title="basic.vue"
<script setup lang="ts">
import { ChevronDownIcon } from "@lucide/vue"
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"

const items = [
  {
    value: "shipping",
    label: "What are your shipping options?",
    content: [
      "We offer standard (5 to 7 days), express (2 to 3 days) and overnight shipping.",
      "Every order ships with tracking, and orders over $50 ship free.",
    ],
  },
  {
    value: "returns",
    label: "What is your return policy?",
    content: [
      "Return any unused item in its original packaging within 30 days. Refunds arrive within 5 to 7 business days.",
    ],
  },
  {
    value: "support",
    label: "How can I reach support?",
    content: [
      "Write to us by email or chat, or call us. We answer within 24 hours on business days.",
    ],
  },
]
</script>

<template>
  <Accordion :default-value="['shipping']">
    <AccordionItem v-for="item in items" :key="item.value" :value="item.value">
      <AccordionHeader>
        <AccordionTrigger>
          {{ item.label }}
          <ChevronDownIcon aria-hidden="true" />
        </AccordionTrigger>
      </AccordionHeader>
      <AccordionPanel>
        <p v-for="paragraph in item.content" :key="paragraph">
          {{ paragraph }}
        </p>
      </AccordionPanel>
    </AccordionItem>
  </Accordion>
</template>
```

Press “What is your return policy?”. Its answer opens and the shipping answer closes. Press the same heading again to close it.

## Installation

```bash
npm install @ui-sdk/vue @ui-sdk/core
```

## Composition

Use the following composition to build an `Accordion`:

```text
Accordion
├── AccordionItem
│   ├── AccordionHeader
│   │   └── AccordionTrigger
│   └── AccordionPanel
└── AccordionItem
    ├── AccordionHeader
    │   └── AccordionTrigger
    └── AccordionPanel
```

Give every item a unique `value`. Put its trigger inside a heading, then add the panel it opens. The accordion's value is always an array of open item values, even when only one can be open.

`AccordionHeader` renders an `h3` by default. Use a heading level that fits the surrounding document. Tab moves between triggers; Enter or Space opens and closes their panels. Arrow keys, Home and End do nothing here: the APG removed them from the pattern, and a screen reader’s heading navigation already reaches each trigger.

## Usage

Import the parts and put them together:

```vue
<script setup lang="ts">
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"
</script>

<template>
  <Accordion>
    <AccordionItem value="shipping">
      <AccordionHeader>
        <AccordionTrigger>Shipping</AccordionTrigger>
      </AccordionHeader>
      <AccordionPanel>Orders arrive in five to seven days.</AccordionPanel>
    </AccordionItem>
  </Accordion>
</template>
```

## Build Your Own

`@ui-sdk/vue/accordion` comes with a ready-made Accordion. If you'd like to build your own, with your own names, start from the `accordion` primitive in `@ui-sdk/core`:

```ts title="faq.ts"
import { accordion } from "@ui-sdk/core/accordion"
import { createParts } from "@ui-sdk/vue/primitive"

const {
  Root: FaqList,
  Item: FaqItem,
  Header: FaqHeading,
  Trigger: FaqQuestion,
  Panel: FaqAnswer,
} = createParts(accordion, {
  root: "div",
  item: "div",
  header: "h3",
  trigger: "button",
  panel: "div",
})

export { FaqAnswer, FaqHeading, FaqItem, FaqList, FaqQuestion }
```

```vue
<template>
  <FaqList>
    <FaqItem value="shipping">
      <FaqHeading>
        <FaqQuestion>What are your shipping options?</FaqQuestion>
      </FaqHeading>
      <FaqAnswer>Standard, express and overnight.</FaqAnswer>
    </FaqItem>
  </FaqList>
</template>
```

Each part keeps the behavior, state and data attributes of its ready-made counterpart. See [Rendering](/docs/vue/rendering) and [Custom Parts](/docs/vue/custom-parts) for more.

## Multiple

Add `multiple` to let several items stay open. Opening one then leaves the others as they are.

```vue title="multiple.vue"
<script setup lang="ts">
import { ChevronDownIcon } from "@lucide/vue"
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"

const items = [
  {
    value: "notifications",
    label: "Notification settings",
    content: "Choose what we email you about, and how often.",
  },
  {
    value: "privacy",
    label: "Privacy and security",
    content: "Turn on two-factor authentication and review signed-in devices.",
  },
  {
    value: "billing",
    label: "Billing and subscription",
    content: "Update your payment method and download past invoices.",
  },
]
</script>

<template>
  <Accordion multiple :default-value="['notifications']">
    <AccordionItem v-for="item in items" :key="item.value" :value="item.value">
      <AccordionHeader>
        <AccordionTrigger>
          {{ item.label }}
          <ChevronDownIcon aria-hidden="true" />
        </AccordionTrigger>
      </AccordionHeader>
      <AccordionPanel>
        {{ item.content }}
      </AccordionPanel>
    </AccordionItem>
  </Accordion>
</template>
```

Open Privacy and security. Notification settings stays open; close either section independently.

## Disabled

Set `disabled` on an item or on a single trigger to prevent changes, or on the accordion to disable every item. Disabled triggers stay in the tab order so people can still discover them. A disabled `<fieldset>` around the accordion disables it too.

```vue title="disabled.vue"
<script setup lang="ts">
import { ChevronDownIcon } from "@lucide/vue"
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"

const items = [
  {
    value: "access",
    label: "Can I access my account history?",
    content:
      "Yes. Every order and payment from the last five years is in your account.",
  },
  {
    value: "premium",
    label: "Premium feature information",
    content:
      "Premium includes priority support and early access to new features.",
    disabled: true,
  },
  {
    value: "email",
    label: "How do I update my email address?",
    content:
      "Open Settings, then Account, and change it there. We'll send a confirmation link.",
  },
]
</script>

<template>
  <Accordion>
    <AccordionItem
      v-for="item in items"
      :key="item.value"
      :value="item.value"
      :disabled="item.disabled"
    >
      <AccordionHeader>
        <AccordionTrigger>
          {{ item.label }}
          <ChevronDownIcon aria-hidden="true" />
        </AccordionTrigger>
      </AccordionHeader>
      <AccordionPanel>
        {{ item.content }}
      </AccordionPanel>
    </AccordionItem>
  </Accordion>
</template>
```

Tab to Premium feature information. It stays focusable, and pressing it leaves its panel closed. Try “How do I update my email address?” instead.

<span id="behavior-and-options" />

## Collapsible

Set `:collapsible="false"` when the open item should stay open until another item replaces it. Pair it with `:default-value="['overview']"` so a panel starts open.

The open trigger reports `aria-disabled="true"` because pressing it leaves its panel open.

```vue
<Accordion :collapsible="false" :default-value="['overview']" />
```

```vue title="collapsible.vue"
<script setup lang="ts">
import { ChevronDownIcon } from "@lucide/vue"
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"

const items = [
  {
    value: "overview",
    label: "Overview",
    content: "A summary of the project, its goals and its owners.",
  },
  {
    value: "timeline",
    label: "Timeline",
    content: "Kickoff in March, beta in June and launch in September.",
  },
  {
    value: "budget",
    label: "Budget",
    content: "Approved for two engineers and one designer for six months.",
  },
]
</script>

<template>
  <Accordion :collapsible="false" :default-value="['overview']">
    <AccordionItem v-for="item in items" :key="item.value" :value="item.value">
      <AccordionHeader>
        <AccordionTrigger>
          {{ item.label }}
          <ChevronDownIcon aria-hidden="true" />
        </AccordionTrigger>
      </AccordionHeader>
      <AccordionPanel>
        {{ item.content }}
      </AccordionPanel>
    </AccordionItem>
  </Accordion>
</template>
```

Open Timeline, then press it again. It stays open until you choose another heading.

## Controlled

Use `v-model:value` to own the open items. [State and Events](/docs/vue/state-and-events) covers the shared pattern.

An item can refuse a change: call `details.cancel()` in its `@open-change` callback. Item callbacks run before the accordion's `@value-change`, including the item that would close when another opens. Canceling any one of them cancels the whole change. `@value-change` also gets the [reason](#reasons) for the change.

```vue title="controlled.vue"
<script setup lang="ts">
import { ChevronDownIcon } from "@lucide/vue"
import type { ChangeDetails } from "@ui-sdk/core"
import { createAccordionController } from "@ui-sdk/core/accordion"
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"
import { ref } from "vue"

const items = [
  {
    value: "account",
    label: "Account",
    content: "Your name, email address and profile photo.",
  },
  {
    value: "security",
    label: "Security",
    content: "Your password, passkeys and two-factor authentication.",
  },
  {
    value: "sessions",
    label: "Sessions",
    content: "Devices signed in to your account in the last 30 days.",
  },
]

const accordion = createAccordionController()

const value = ref(["account"])

function confirmClose(item: string, open: boolean, details: ChangeDetails) {
  if (
    !open &&
    item === "security" &&
    !window.confirm("Close the security settings?")
  ) {
    details.cancel()
  }
}
</script>

<template>
  <div>
    <div data-slot="controls">
      <button type="button" @click="accordion.open('security')">
        Review security
      </button>
    </div>
    <Accordion v-model:value="value" multiple :controller="accordion">
      <AccordionItem
        v-for="item in items"
        :key="item.value"
        :value="item.value"
        @open-change="
          (open: boolean, details: ChangeDetails) =>
            confirmClose(item.value, open, details)
        "
      >
        <AccordionHeader>
          <AccordionTrigger>
            {{ item.label }}
            <ChevronDownIcon aria-hidden="true" />
          </AccordionTrigger>
        </AccordionHeader>
        <AccordionPanel>
          {{ item.content }}
        </AccordionPanel>
      </AccordionItem>
    </Accordion>
  </div>
</template>
```

Press Security to open it, then press it again. Cancel the confirmation and Security stays open; accept it and the section closes.

## Keep Mounted

A closed panel normally unmounts. Add `keep-mounted` to one panel or the whole accordion to keep its content hidden in the page. This preserves local state, such as a draft in a field.

```vue title="keep-mounted.vue"
<script setup lang="ts">
import { ChevronDownIcon } from "@lucide/vue"
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"
import { Field, FieldLabel } from "@ui-sdk/vue/field"
import { Textarea } from "@ui-sdk/vue/textarea"
</script>

<template>
  <Accordion :default-value="['reply']">
    <AccordionItem value="reply">
      <AccordionHeader>
        <AccordionTrigger>
          Reply to this thread
          <ChevronDownIcon aria-hidden="true" />
        </AccordionTrigger>
      </AccordionHeader>
      <AccordionPanel keep-mounted>
        <Field>
          <FieldLabel>Message</FieldLabel>
          <Textarea rows="3" placeholder="Write a reply…" />
        </Field>
      </AccordionPanel>
    </AccordionItem>
    <AccordionItem value="formatting">
      <AccordionHeader>
        <AccordionTrigger>
          Formatting
          <ChevronDownIcon aria-hidden="true" />
        </AccordionTrigger>
      </AccordionHeader>
      <AccordionPanel>
        <p>Use **bold**, _italics_ and `code`. Links paste as previews.</p>
      </AccordionPanel>
    </AccordionItem>
  </Accordion>
</template>
```

Write a message, switch to Formatting, then return to Reply to this thread. Your draft is still there.

## Find in Page

Add `hidden-until-found` to keep closed panels available to the browser's Find command. A match opens the item immediately, without an animation, with the [reason](#reasons) `find-in-page`.

```vue title="find-in-page.vue"
<script setup lang="ts">
import { ChevronDownIcon } from "@lucide/vue"
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"

const items = [
  {
    value: "fruit",
    label: "Which fruit do you stock?",
    content: "Apples, pears, mangoes and, in summer, pineapple.",
  },
  {
    value: "organic",
    label: "Is it organic?",
    content: "Everything we stock is certified organic.",
  },
  {
    value: "delivery",
    label: "When do you deliver?",
    content: "Every weekday morning before 10.",
  },
]
</script>

<template>
  <Accordion hidden-until-found>
    <AccordionItem v-for="item in items" :key="item.value" :value="item.value">
      <AccordionHeader>
        <AccordionTrigger>
          {{ item.label }}
          <ChevronDownIcon aria-hidden="true" />
        </AccordionTrigger>
      </AccordionHeader>
      <AccordionPanel>
        {{ item.content }}
      </AccordionPanel>
    </AccordionItem>
  </Accordion>
</template>
```

Use your browser’s Find command to search for “pineapple”. The closed “Which fruit do you stock?” panel opens to reveal the match.

<span id="deep-links" />

A link to an element inside a closed panel can reveal it too. Give the target an `id` and link to it with a hash, such as `href="#refund-timeline"`.

```vue title="deep-link.vue"
<script setup lang="ts">
import { ChevronDownIcon } from "@lucide/vue"
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"
</script>

<template>
  <div>
    <nav data-slot="controls" aria-label="Jump to">
      <a href="#refund-timeline">Jump to the refund timeline</a>
      <a href="#return-label">Print a return label</a>
    </nav>
    <Accordion hidden-until-found>
      <AccordionItem value="returns">
        <AccordionHeader>
          <AccordionTrigger>
            Returns
            <ChevronDownIcon aria-hidden="true" />
          </AccordionTrigger>
        </AccordionHeader>
        <AccordionPanel>
          <div data-slot="stack">
            <p>
              Return any unused item in its original packaging within 30 days.
            </p>
            <p id="return-label">
              To print a return label, open the order and choose Return. The
              label is free.
            </p>
          </div>
        </AccordionPanel>
      </AccordionItem>
      <AccordionItem value="refunds">
        <AccordionHeader>
          <AccordionTrigger>
            Refunds
            <ChevronDownIcon aria-hidden="true" />
          </AccordionTrigger>
        </AccordionHeader>
        <AccordionPanel>
          <div data-slot="stack">
            <p>Refunds go back to the card you paid with.</p>
            <p id="refund-timeline">
              Timeline: we inspect the item within 2 days of receiving it, and
              your bank shows the refund 5 to 7 business days later.
            </p>
          </div>
        </AccordionPanel>
      </AccordionItem>
      <AccordionItem value="exchanges">
        <AccordionHeader>
          <AccordionTrigger>
            Exchanges
            <ChevronDownIcon aria-hidden="true" />
          </AccordionTrigger>
        </AccordionHeader>
        <AccordionPanel>
          <div data-slot="stack">
            <p>
              Start a return, choose Exchange and pick the new size. Shipping
              both ways is free.
            </p>
          </div>
        </AccordionPanel>
      </AccordionItem>
    </Accordion>
  </div>
</template>
```

Press Jump to the refund timeline. The closed Refunds panel opens and the browser moves to the linked paragraph.

With `hidden-until-found`, Vue's server render writes `hidden="until-found"`, so closed panels are findable from the start. For an initial URL hash, [open the item explicitly](#url-hash).

## Animation

Each part has a `data-slot`, such as `accordion-panel`. The panel exposes its measured height as `--accordion-panel-height`. Animate that height to or from zero with `data-starting-style` and `data-ending-style`:

```css
[data-slot="accordion-panel"] {
  height: var(--accordion-panel-height);
  overflow: hidden;
  transition: height 0.15s;

  &:is([data-starting-style], [data-ending-style]) {
    height: 0;
  }
}
```

The panel stays mounted until its exit animation finishes. An item's `@open-change-complete` runs afterward with the open state. A panel that starts open appears right away, with no animation and no completion callback.

```vue title="animation.vue"
<script setup lang="ts">
import { ChevronDownIcon } from "@lucide/vue"
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"

const items = [
  {
    value: "one",
    label: "Why animate the height?",
    content: "So the content below slides instead of jumping.",
  },
  {
    value: "two",
    label: "Where does the height come from?",
    content:
      "The panel measures itself and writes the result to a CSS variable while it animates.",
  },
  {
    value: "three",
    label: "Does it animate on first paint?",
    content: "No. Panels open on the server or on mount show at once.",
  },
]
</script>

<template>
  <Accordion :default-value="['one']">
    <AccordionItem v-for="item in items" :key="item.value" :value="item.value">
      <AccordionHeader>
        <AccordionTrigger>
          {{ item.label }}
          <ChevronDownIcon aria-hidden="true" />
        </AccordionTrigger>
      </AccordionHeader>
      <AccordionPanel>
        {{ item.content }}
      </AccordionPanel>
    </AccordionItem>
  </Accordion>
</template>
```

Open or close an item. Its panel animates its height.

## Expand All

With `multiple`, a controller's `openAll()` opens every enabled item. `closeAll()` closes every item that may close. [Controllers](/docs/vue/controllers) explains how to connect one.

```vue title="expand-all.vue"
<script setup lang="ts">
import { ChevronDownIcon } from "@lucide/vue"
import type { ChangeDetails } from "@ui-sdk/core"
import { createAccordionController } from "@ui-sdk/core/accordion"
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"
import type { ComponentPublicInstance } from "vue"

const weeks = [
  {
    value: "week-1",
    label: "Week 1: Foundations",
    content:
      "Set up your editor, meet the command line and write your first script.",
  },
  {
    value: "week-2",
    label: "Week 2: Data and types",
    content:
      "Strings, numbers, lists and objects, and how to tell them apart when a program runs.",
  },
  {
    value: "week-3",
    label: "Week 3: Control flow",
    content:
      "Conditions, loops and functions. The project this week is a small text adventure.",
  },
  {
    value: "week-4",
    label: "Week 4: Working with files",
    content:
      "Read and write files, parse CSV and JSON, and handle the errors that come with them.",
  },
  {
    value: "week-5",
    label: "Week 5: Final project",
    content:
      "Build a tool you'll use yourself, then present it to the group in a five-minute demo.",
  },
]

const syllabus = createAccordionController()

const elements = new Map<string, HTMLElement>()
function setElement(
  value: string,
  instance: Element | ComponentPublicInstance | null
) {
  if (instance && "$el" in instance) {
    elements.set(value, instance.$el as HTMLElement)
  } else {
    elements.delete(value)
  }
}

let pressed: string | null = null
function openChange(value: string, open: boolean, details: ChangeDetails) {
  if (open && details.reason === "trigger-press") {
    pressed = value
  } else if (pressed === value) {
    pressed = null
  }
}

function openChangeComplete(value: string, open: boolean) {
  if (!open || pressed !== value) {
    return
  }
  pressed = null
  elements.get(value)?.scrollIntoView({ block: "nearest", behavior: "smooth" })
}
</script>

<template>
  <div>
    <div data-slot="controls">
      <button type="button" @click="syllabus.openAll()">Expand all</button>
      <button type="button" @click="syllabus.closeAll()">Collapse all</button>
    </div>
    <div data-slot="scroll">
      <Accordion multiple :controller="syllabus">
        <AccordionItem
          v-for="week in weeks"
          :key="week.value"
          :ref="(instance) => setElement(week.value, instance)"
          :value="week.value"
          @open-change="
            (open: boolean, details: ChangeDetails) =>
              openChange(week.value, open, details)
          "
          @open-change-complete="
            (open: boolean) => openChangeComplete(week.value, open)
          "
        >
          <AccordionHeader>
            <AccordionTrigger>
              {{ week.label }}
              <ChevronDownIcon aria-hidden="true" />
            </AccordionTrigger>
          </AccordionHeader>
          <AccordionPanel>
            {{ week.content }}
          </AccordionPanel>
        </AccordionItem>
      </Accordion>
    </div>
  </div>
</template>
```

Press Expand all or Collapse all. Open an individual week near the bottom to scroll it into view after its panel opens.

## Nested

Put another accordion inside a panel when a section has its own expandable sections. Each accordion tracks its own items. Give the inner headings a lower level than the outer headings.

```vue title="nested.vue"
<script setup lang="ts">
import { ChevronDownIcon } from "@lucide/vue"
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"

const sections: {
  value: string
  label: string
  content?: string
  topics?: { value: string; label: string; content: string }[]
}[] = [
  {
    value: "profile",
    label: "Profile",
    content: "Your name, photo and the email address people see.",
  },
  {
    value: "notifications",
    label: "Notifications",
    topics: [
      {
        value: "email",
        label: "Email",
        content: "A weekly digest, and mentions as they happen.",
      },
      {
        value: "push",
        label: "Push",
        content: "Direct messages and replies to your comments.",
      },
    ],
  },
  {
    value: "billing",
    label: "Billing",
    topics: [
      {
        value: "payment",
        label: "Payment methods",
        content: "A Visa card ending in 4242, used for every renewal.",
      },
      {
        value: "invoices",
        label: "Invoices",
        content: "Download a PDF of any invoice from the last two years.",
      },
    ],
  },
]
</script>

<template>
  <Accordion :default-value="['notifications']">
    <AccordionItem
      v-for="section in sections"
      :key="section.value"
      :value="section.value"
    >
      <AccordionHeader>
        <AccordionTrigger>
          {{ section.label }}
          <ChevronDownIcon aria-hidden="true" />
        </AccordionTrigger>
      </AccordionHeader>
      <AccordionPanel>
        <Accordion v-if="section.topics" multiple>
          <AccordionItem
            v-for="topic in section.topics"
            :key="topic.value"
            :value="topic.value"
          >
            <AccordionHeader>
              <template #render="{ props }">
                <h4 v-bind="props">
                  <AccordionTrigger>
                    {{ topic.label }}
                    <ChevronDownIcon aria-hidden="true" />
                  </AccordionTrigger>
                </h4>
              </template>
            </AccordionHeader>
            <AccordionPanel>
              {{ topic.content }}
            </AccordionPanel>
          </AccordionItem>
        </Accordion>
        <div v-else>{{ section.content }}</div>
      </AccordionPanel>
    </AccordionItem>
  </Accordion>
</template>
```

Open Billing, then Invoices inside it. The inner accordion changes without closing Billing.

## FAQ Search

<span id="faq-with-search" />

Combine a search field with a controlled accordion: filter the questions and set `value` to the matching items. The example also highlights matches and leaves the triggers usable while the search is active.

```vue title="search.vue"
<script setup lang="ts">
import { ChevronDownIcon } from "@lucide/vue"
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"
import { computed, ref } from "vue"

const faq = [
  {
    value: "returns",
    question: "What is your return policy?",
    answer:
      "Return any unused item within 30 days. Once it reaches us, your refund is on its way.",
  },
  {
    value: "refunds",
    question: "How long do refunds take?",
    answer:
      "Refunds reach your card within 5 to 7 business days after we receive the item.",
  },
  {
    value: "shipping",
    question: "Do you ship internationally?",
    answer:
      "We ship to 40 countries. Duties are included in the price at checkout.",
  },
  {
    value: "tracking",
    question: "How do I track my order?",
    answer:
      "Every shipping email has a tracking link. You'll also find it under Orders.",
  },
  {
    value: "exchange",
    question: "Can I exchange an item for another size?",
    answer:
      "Yes. Start a return, choose Exchange and pick the new size. Shipping is free.",
  },
  {
    value: "gift",
    question: "Can I send an order as a gift?",
    answer:
      "Add a gift note at checkout and we'll leave the prices off the packing slip.",
  },
]

function matches(question: (typeof faq)[number], query: string) {
  const search = query.trim().toLowerCase()
  return (
    !search ||
    question.question.toLowerCase().includes(search) ||
    question.answer.toLowerCase().includes(search)
  )
}

function highlight(text: string, query: string) {
  const search = query.trim().toLowerCase()
  if (!search) {
    return [{ text, match: false }]
  }
  const parts: { text: string; match: boolean }[] = []
  let start = 0
  for (let index = text.toLowerCase().indexOf(search); index !== -1;) {
    if (index > start) {
      parts.push({ text: text.slice(start, index), match: false })
    }
    parts.push({ text: text.slice(index, index + search.length), match: true })
    start = index + search.length
    index = text.toLowerCase().indexOf(search, start)
  }
  if (start < text.length) {
    parts.push({ text: text.slice(start), match: false })
  }
  return parts
}

const query = ref("")
const value = ref<string[]>([])
const results = computed(() =>
  faq.filter((question) => matches(question, query.value))
)

function search(next: string) {
  query.value = next
  value.value = next.trim()
    ? results.value.map((question) => question.value)
    : []
}
</script>

<template>
  <div>
    <div data-slot="controls">
      <input
        type="search"
        aria-label="Search questions"
        placeholder="Search questions…"
        :value="query"
        @input="search(($event.target as HTMLInputElement).value)"
      />
    </div>
    <Accordion v-model:value="value" multiple>
      <AccordionItem
        v-for="question in results"
        :key="question.value"
        :value="question.value"
      >
        <AccordionHeader>
          <AccordionTrigger>
            <span>
              <template
                v-for="(part, index) in highlight(question.question, query)"
                :key="index"
              >
                <mark v-if="part.match">{{ part.text }}</mark>
                <template v-else>{{ part.text }}</template>
              </template>
            </span>
            <ChevronDownIcon aria-hidden="true" />
          </AccordionTrigger>
        </AccordionHeader>
        <AccordionPanel>
          <template
            v-for="(part, index) in highlight(question.answer, query)"
            :key="index"
          >
            <mark v-if="part.match">{{ part.text }}</mark>
            <template v-else>{{ part.text }}</template>
          </template>
        </AccordionPanel>
      </AccordionItem>
    </Accordion>
    <p data-slot="hint" role="status">
      <template v-if="results.length === 0"
        >No questions match “{{ query }}”.</template
      >
    </p>
  </div>
</template>
```

Search for “refund” to show and open matching answers. Try “zzz” for the empty result, then clear the search to restore all questions.

## URL Hash

<span id="open-the-item-in-the-url-hash" />

A hash can name an item's `value` instead of an element inside its panel. Read it after mount and on `hashchange`, then open and focus the matching item through your controller:

```ts
const value = decodeURIComponent(location.hash.slice(1))
if (items.some((item) => item.value === value)) {
  accordion.open(value)
  accordion.focus(value)
}
```

Check the value against your items first. A controller can hold a value even when no item renders it. Remove the `hashchange` listener when the component unmounts.

## Query String

<span id="keep-open-items-in-the-query-string" />

Use `open` query parameters when several items should be shareable. Read the initial values from your router on the server, then write accepted changes back to the URL:

```ts
function saveOpenItems(value: string[]) {
  const url = new URL(location.href)
  url.searchParams.delete("open")
  for (const item of value) url.searchParams.append("open", item)
  history.replaceState(null, "", url)
}
```

Call this from `@value-change` after updating your state. If your app already has a router, use its navigation API instead.

## Scroll into View

<span id="scroll-an-item-into-view" />

Scroll after `@open-change-complete`, when the panel has its full height. Scrolling in `@open-change` would measure it before it opens. The [Expand All example](#expand-all) shows the full setup and scrolls only when someone opens a single item.

## Custom Rendering

<span id="render-functions" />

Use a `#render` slot to choose another heading level or element. [Parts and Composition](/docs/vue/parts-and-composition#choose-the-element) covers custom elements and part state. Accordion's states are listed under [State](#state).

```vue title="render.vue"
<script setup lang="ts">
import {
  Accordion,
  AccordionHeader,
  AccordionItem,
  AccordionPanel,
  AccordionTrigger,
} from "@ui-sdk/vue/accordion"

const steps = [
  {
    value: "install",
    label: "Install the package",
    content: "Add it with your package manager. It has no dependencies.",
  },
  {
    value: "import",
    label: "Import the parts",
    content: "Import the accordion parts you need from the package.",
  },
  {
    value: "style",
    label: "Style it",
    content: "Every part renders its state as data attributes you can style.",
  },
]
</script>

<template>
  <Accordion multiple :default-value="['install']">
    <AccordionItem v-for="step in steps" :key="step.value" :value="step.value">
      <AccordionHeader>
        <template #render="{ props }">
          <h4 v-bind="props">
            <AccordionTrigger>
              <template #render="{ props: triggerProps, state: triggerState }">
                <button v-bind="triggerProps">
                  <span
                    data-slot="hint"
                    v-if="triggerState.index >= 0"
                    aria-hidden="true"
                  >
                    {{ String(triggerState.index + 1).padStart(2, "0") }}
                  </span>
                  <span>{{ step.label }}</span>
                  <span data-slot="hint" aria-hidden="true">
                    {{ triggerState.open ? "Hide" : "Show" }}
                  </span>
                </button>
              </template>
            </AccordionTrigger>
          </h4>
        </template>
      </AccordionHeader>
      <AccordionPanel>
        {{ step.content }}
      </AccordionPanel>
    </AccordionItem>
  </Accordion>
</template>
```

Each step is an h4 with its number and a Show or Hide hint that follows its open state. Open Import the parts to see it update.

## Styling

Style the parts with the attributes below. This turns the chevron as its panel opens, mirrors it in right to left with `:dir(rtl)`, and dims disabled triggers:

```css
[data-slot="accordion-trigger"] {
  & > svg {
    rotate: -90deg;

    &:dir(rtl) {
      rotate: 90deg;
    }
  }

  &[data-open] > svg {
    rotate: 0deg;
  }

  &[data-disabled] {
    color: gray;
  }
}
```

### AccordionPanel
- `--accordion-panel-height`: The panel's content height in pixels while it animates, auto once open and 0px while closed.
- `--accordion-panel-width`: The panel's content width, the same way. For accordions that open sideways.

## Data Attributes

### Accordion
`[data-slot="accordion"]`

- `data-disabled`: Present when the whole accordion is disabled.

### AccordionItem
`[data-slot="accordion-item"]`

- `data-open`: Present while the item is open.
- `data-closed`: Present while the item is closed, including while its panel animates out.
- `data-disabled`: Present when the item can't open or close.

### AccordionHeader
`[data-slot="accordion-header"]`

- `data-open`: Present while the item is open.
- `data-closed`: Present while the item is closed, including while its panel animates out.
- `data-disabled`: Present when the item can't open or close.

### AccordionTrigger
`[data-slot="accordion-trigger"]`

- `data-open`: Present while the item is open.
- `data-closed`: Present while the item is closed, including while its panel animates out.
- `data-disabled`: Present when the item can't open or close.

### AccordionPanel
`[data-slot="accordion-panel"]`

- `data-open`: Present while the item is open.
- `data-closed`: Present while the item is closed, including while its panel animates out.
- `data-disabled`: Present when the item can't open or close.
- `data-starting-style`: Present for a panel's first frame. Style the state you animate from.
- `data-ending-style`: Present while a panel animates closed. Style the state you animate to.

## API Reference

Props are the same as below, and callbacks are events. Headers, triggers and panels take their item's value
from the item.

### Accordion

- `value?` (`T[]`): The open items' values. Pass it to control the accordion.
- `defaultValue?` (`T[]`): The items open at first, when uncontrolled.
- `@value-change` (`((value: T[], details: ChangeDetails<AccordionValueChangeReason>) => void)`): Runs when items want to open or close. `details.reason` says why, and `details.cancel()` stops it.
- `multiple?` (`boolean`): Whether several items can be open at once. Otherwise opening one closes the others.
- `collapsible?` (`boolean`): Whether the open item can close when only one may be open. With `false`, one item always stays open and its trigger reports it can't be pressed.
- `disabled?` (`boolean`): Stops every item from opening or closing. Triggers stay focusable.
- `keepMounted?` (`boolean`): Whether closed panels stay in the page, hidden.
- `hiddenUntilFound?` (`boolean`): Keeps closed panels in the page as `hidden="until-found"`, so the browser's find in page can match their text and open them.
- `controller?` (`object`): Opens and closes items from anywhere. Create one with `createAccordionController()`.
- `debug?` (`boolean`): Logs every state change with its reason to the console, in development builds.

### AccordionItem

- `disabled?` (`boolean`): Stops the item from opening or closing. Its trigger stays focusable.
- `@open-change` (`((open: boolean, details: ChangeDetails<AccordionValueChangeReason>) => void)`): Runs before the item opens or closes, before the accordion's `@value-change`. `details.cancel()` stops it.
- `@open-change-complete` (`((open: boolean) => void)`): Runs once the item's panel has finished opening or closing, after any animation.
- `value?` (`T`): Identifies the item. The accordion's value lists the open items' values. Defaults to a generated id.

### AccordionHeader

The header takes no options of its own, only the props of the element it renders.

### AccordionTrigger

- `disabled?` (`boolean`): Stops this trigger from opening or closing the item. It stays focusable.

### AccordionPanel

- `keepMounted?` (`boolean`): Whether the panel stays in the page, hidden, while closed. Overrides the accordion's.
- `hiddenUntilFound?` (`boolean`): Whether the panel stays findable with `hidden="until-found"` while closed. Overrides the accordion's.
### State

What render functions, state-based class names and slots receive, per part.

`Accordion`:

- `value` (`T[]`): The open items' values.
- `disabled` (`boolean`): Whether the whole accordion is disabled, by its `disabled` option or a disabled fieldset around it.
- `multiple` (`boolean`): Whether several items can be open at once.

`AccordionItem`, `AccordionHeader`, `AccordionTrigger` and `AccordionPanel`:

- `open` (`boolean`): Whether the accordion's `value` holds this item's value.
- `disabled` (`boolean`): Whether the item can't open or close.
- `index` (`number`): The item's position among the accordion's items, from 0. -1 until it's in the page.

### Reasons

`details.reason` says why items opened or closed, for `@value-change` and every item's `@open-change`.

- `trigger-press` (`MouseEvent | KeyboardEvent | TouchEvent`): Click, tap, Enter or Space on the part that opens, closes or toggles. Arrow keys that open a menu or submenu count too. A tap on a combobox's input that opens a sheet reports its `touchend`.
- `find-in-page` (`Event`): The browser's find in page matched hidden content.
- `imperative` (`none`): A controller or `api` call, or a property set on a web component.

### Controller

Create one with `createAccordionController()` and pass it as `controller`.

Every write method takes an optional `{ reason, event }`, runs the item and accordion callbacks like a press, and returns `false` when the change is canceled or does nothing.

- `getValue()` (`() => T[]`): The open items' values.
- `setValue(value, options?)` (`(value: T[], options?: AccordionChangeOptions | undefined) => boolean`): Sets the open items. Only the first counts unless `multiple` is set. Returns false when canceled.
- `isOpen(value)` (`(value: T) => boolean`): Whether an item is open.
- `open(value, options?)` (`(value: T, options?: AccordionChangeOptions | undefined) => boolean`): Opens an item. With one item open at a time, closes the others.
- `close(value, options?)` (`(value: T, options?: AccordionChangeOptions | undefined) => boolean`): Closes an item, unless it's the one item that must stay open.
- `toggle(value, options?)` (`(value: T, options?: AccordionChangeOptions | undefined) => boolean`): Opens a closed item, or closes an open one.
- `openAll(options?)` (`(options?: AccordionChangeOptions | undefined) => boolean`): Opens every enabled item. Only when `multiple` is set.
- `closeAll(options?)` (`(options?: AccordionChangeOptions | undefined) => boolean`): Closes every item that may close.
- `focus(value?)` (`(value?: T | undefined) => void`): Moves focus to an item's trigger, or the first trigger.

### Events

Events get the new state first, then the details.

| Binding                 | On              | Receives                                                       |
| ----------------------- | --------------- | -------------------------------------------------------------- |
| `v-model:value`         | `Accordion`     | The open items                                                 |
| `@value-change`         | `Accordion`     | `(value, details)`: the open items, and the [reason](#reasons) |
| `@open-change`          | `AccordionItem` | `(open, details)`, before `@value-change`                      |
| `@open-change-complete` | `AccordionItem` | `(open)`, after the panel's animation                          |

## Accessibility

The accordion follows the [WAI-ARIA accordion pattern](https://www.w3.org/WAI/ARIA/apg/patterns/accordion/). Every line below is an automated test.

**Expanding and collapsing**

- The default item is expanded and shows its panel.
- Clicking a collapsed trigger expands it and collapses the open one.
- Clicking an expanded trigger collapses it.
- Clicking a disabled trigger does nothing.
- A change can be canceled.
- Without a default value, every item starts collapsed.
- A default value can expand several items.

**Multiple**

- Items expand and collapse independently.
- Every item can be expanded at once.

**Disabled**

- A disabled item's trigger is marked disabled and stays focusable.
- A disabled accordion disables every trigger.

**Keyboard**

- Tab moves through every trigger in order, disabled ones included.
- Enter toggles the focused trigger's panel.
- Space toggles the focused trigger's panel.
- Enter on a disabled trigger does nothing.
- Tab moves from an expanded trigger into its panel.
- Keys pressed in quick succession are never lost.
- Arrow keys leave focus where it is.

**Structure**

- Each trigger sits in a heading.
- The trigger controls its panel, and the panel is labelled by its trigger.

**Mounting**

- Collapsed panels leave the page by default.
- With keepMounted, collapsed panels stay in the page, hidden.
- With keepMounted, a class that sets display doesn't show collapsed panels.
- With hiddenUntilFound, collapsed panels stay findable.
- Finding text in a collapsed panel expands it.
- Following a link into a collapsed panel expands it.
- The browser's own find expands a collapsed panel.

Runs in React, Vue and web components.

Beyond the pattern's baseline:

**Enhancements**

- With collapsible off, the open trigger is marked disabled and stays open.
- Closing a panel that holds focus moves focus to its trigger.
- A canceled find in page keeps the panel hidden until found.
- An infinite exit animation still unmounts the panel.
- A controller expands and collapses items from anywhere.
- An item's onOpenChangeComplete runs once its panel has finished animating.
- Find in page opens a panel at once, without an animation.

Runs in React, Vue and web components.

Every panel is a region labelled by its trigger, so screen readers can list open panels as landmarks. With many panels open at once, such as `multiple` with Expand all, keep the number of items modest so that list stays short.

Screen readers hear the same thing in each tested framework, recorded by a virtual screen reader:

- Announcements while using the accordion with a keyboard.

Runs in React, Vue and web components.