bootstrap-vue/src/components/toast/README.md

BootstrapVue, with over 40 plugins and more than 75 custom components, provides one of the most comprehensive implementations of Bootstrap v4 components and grid system for Vue.js. With extensive and automated WAI-ARIA accessibility markup.

# Toasts

> Push notifications to your visitors with a `<b-toast>` and `<b-toaster>`, lightweight components
> which are easily customizable for generating alert messages.

Toasts are lightweight notifications designed to mimic the push notifications that have been
popularized by mobile and desktop operating systems.

Toasts are intended to be small interruptions to your visitors or users, and therefore should
contain minimal, to-the-point, non-interactive content.

<div class="alert alert-warning">
  <p class="mb-0">
    <strong>BETA warning:</strong><br>
    Toasts are in their preliminary stages of being developed, and usage and custom CSS is subject
    to change in future releases.
  </p>
</div>

## Overview

To encourage extensible and predictable toasts, we recommend providing a header (title) and body.
Toast headers use the style `'display: flex'`, allowing easy alignment of content thanks to
Bootstrap's [margin and flexbox utility classes](/docs/reference/utility-classes).

Toasts are slightly translucent, too, so they blend over whatever they might appear over. For
browsers that support the `backdrop-filter` CSS property, they also attempt to blur the elements
under the toast.

```html
<template>
  <div class="p-3 bg-secondary progress-bar-striped" style="min-height: 170px;">
    <b-button class="mb-2" variant="primary" @click="$bvToast.show('example-toast')">
      Show toast
    </b-button>
    <b-toast id="example-toast" title="BootstrapVue" static no-auto-hide>
      Hello, world! This is a toast message.
    </b-toast>
  </div>
</template>

<!-- toast-intro.vue -->
```

**Note:** we are using the `static` prop in the above example to render the toast in-pace in the
document, rather than transporting it to a `<b-toaster>` target container. And we have added classes
`bg-secondary` and `progress-bar-striped` to the outer `<div>` for illustrative purposes of toast
transparency only.

### Toast features and notes

- Toasts can be generated on demand via the injection `this.$bvToast` object, or manually created
  using the `<b-toast>` component.
- Toasts will auto hide after a default of 5 seconds (5000ms). The duration can be changed via the
  `auto-hide-delay` prop (value is specified in milliseconds), and disabled with the `no-auto-hide`
  prop.
- When auto-hide is enabled, and you hover over the toast, the auto-hide countdown will be paused
  until you un-hover the toast. You can disabled this feature by setting the `no-hover-pause` prop
  to `true`.
- Toasts include a close button on their top right to allow users to manually dismiss them. The
  close button can be removed via the `no-close-button` prop.
- Titles are optional, but should be included, titles are rendered inside a `<strong>` element,
  unless using the `toast-title` slot.
- If you disable the auto-hide feature, avoid hiding the close button, or if you hide the close
  button be sure to allow the toast to auto-dismiss.
- Toast transparency can be disabled by setting the `solid` prop to `true`.
- Toasts will show inside a named `<b-toaster>` target component. BootstrapVue comes with several
  pre-defined toaster targets. Toasts will check for the named toaster in the document before they
  are shown, and will dynamically create the named toaster target if one is not found.
- Toaster targets are defined completely with CSS for controlling the positioning of the contained
  `<b-toast>` components.
- Toasts can can targeted to any named toaster.
- Toasts are wrapped in a `<div>` with class `b-toast` to allow for Vue list-transition support when
  displayed in a toaster component.

BootstrapVue uses [PortalVue](https://portal-vue.linusb.org/) to transport toasts into the toasters.

## Toasts on demand

Generate a dynamic toast from anywhere in your app via the `this.$bvToast` Vue component _instance_
injection, without the need to place a [`<b-toast>`](#b-toast-component) component in your app.

Use the `this.$bvToast.toast()` method to generate on demand toasts. The method accepts two
arguments:

- `message`: the content of the toast body (either a string, or an array of `VNodes`). Required.
  Toasts with an empty message will not be shown. See the [Advanced usage](#advanced-usage) section
  for an example of passing an array of `VNodes` as the message.
- `options`: an optional options object for providing a title and/or additional configuration
  options. The `title` option can be either a string or an array of `VNodes`

The options argument accepts most of the props that the `<b-toast>` component accepts (with the
exception of `static`, and `visible`) in <samp>camelCase</samp> name format instead of
<samp>kebab-case</samp>.

```html
<template>
  <div>
    <b-button @click="makeToast()">Show Toast</b-button>
    <b-button @click="makeToast(true)">Show Toast (appended)</b-button>
  </div>
</template>

<script>
  export default {
    data() {
      return {
        toastCount: 0
      }
    },
    methods: {
      makeToast(append = false) {
        this.toastCount++
        this.$bvToast.toast(`This is toast number ${this.toastCount}`, {
          title: 'BootstrapVue Toast',
          autoHideDelay: 5000,
          appendToast: append
        })
      }
    }
  }
</script>

<!-- toasts-bv-toast-example.vue -->
```

Once a toast which was generated using `this.$bvToast.toast()` has been hidden, it will
automatically be destroyed and removed from the document.

**Notes:**

- The `this.$bvToast` injection is only available when using the full `BootstrapVue` plugin or the
  `Toast` plugin. It is not available if importing just the `b-toast` or `b-toaster` components.
- A new `$bvToast` injection (mixin) is created for each Vue virtual machine (i.e. each instantiated
  component), and is not usable via direct access to the `Vue.prototype`, as it needs access to the
  instance's `this` and `$root` contexts.
- Toasts generated via `this.$bvToast.toast()` are children of the Vue instance that calls the
  `this.$bvToast.toast()` method, and will be hidden and destroyed if that Vue instance (i.e. your
  component or app) is also destroyed.
- Toasts require a message. Toasts on demand with an empty message will silently not be shown.

## Options

Toasts have various options that can control their style and behaviour. Options are available both
as props on the `<b-toast>` component and as properties of the options object passed to
`this.$bvToast.toast()`. When passing options to `this.$bvToast.toast()`, use the
<samp>camelCase</samp> version of the component prop name, i.e. use `noAutoHide` instead of
`no-auto-hide`.

### Title

Add a title to your toast via the `title` option. Just like the toast `message`, the title can be a
simple string, or an array of vNodes. See the [Advanced usage](#advanced-usage) section for an
example of passing an array of `VNodes` as the message and title.

### Transparency

Toasts have a semi-transparent background by default. To disable the default transparency, just set
the `solid` prop to `true`

### Variants

BootstrapVue toasts provide custom CSS to define color variants. Variants follow the standard
Bootstrap v4 variant names. If you have custom SCSS defined Bootstrap color variants, the toast
custom SCSS will automatically create toast variants for you.

```html
<template>
  <div>
    <b-button @click="makeToast()" class="mb-2">Default</b-button>
    <b-button variant="primary" @click="makeToast('primary')" class="mb-2">Primary</b-button>
    <b-button variant="secondary" @click="makeToast('secondary')" class="mb-2">Secondary</b-button>
    <b-button variant="danger" @click="makeToast('danger')" class="mb-2">Danger</b-button>
    <b-button variant="warning" @click="makeToast('warning')" class="mb-2">Warning</b-button>
    <b-button variant="success" @click="makeToast('success')" class="mb-2">Success</b-button>
    <b-button variant="info" @click="makeToast('info')" class="mb-2">Info</b-button>
  </div>
</template>

<script>
  export default {
    methods: {
      makeToast(variant = null) {
        this.$bvToast.toast('Toast body content', {
          title: `Variant ${variant || 'default'}`,
          variant: variant,
          solid: true
        })
      }
    }
  }
</script>

<!-- toast-variants.vue -->
```

### Toaster target

BootstrapVue comes with the following "built-in" toaster names (and associated styles defined in
SCSS):

- `b-toaster-top-right`
- `b-toaster-top-left`
- `b-toaster-top-center`
- `b-toaster-top-full`
- `b-toaster-bottom-right`
- `b-toaster-bottom-left`
- `b-toaster-bottom-center`
- `b-toaster-bottom-full`

```html
<template>
  <div>
    <b-button @click="toast('b-toaster-top-right')" class="mb-2">b-toaster-top-right</b-button>
    <b-button @click="toast('b-toaster-top-left')" class="mb-2">b-toaster-top-left</b-button>
    <b-button @click="toast('b-toaster-top-center')" class="mb-2">b-toaster-top-center</b-button>
    <b-button @click="toast('b-toaster-top-full')" class="mb-2">b-toaster-top-full</b-button>
    <b-button @click="toast('b-toaster-bottom-right', true)" class="mb-2">b-toaster-bottom-right</b-button>
    <b-button @click="toast('b-toaster-bottom-left', true)" class="mb-2">b-toaster-bottom-left</b-button>
    <b-button @click="toast('b-toaster-bottom-center', true)" class="mb-2">b-toaster-bottom-center</b-button>
    <b-button @click="toast('b-toaster-bottom-full', true)" class="mb-2">b-toaster-bottom-full</b-button>
  </div>
</template>

<script>
  export default {
    data() {
      return {
        counter: 0
      }
    },
    methods: {
      toast(toaster, append = false) {
        this.counter++
        this.$bvToast.toast(`Toast ${this.counter} body content`, {
          title: `Toaster ${toaster}`,
          toaster: toaster,
          solid: true,
          appendToast: append
        })
      }
    }
  }
</script>

<!-- toast-targets.vue -->
```

**Notes:**

- Toaster target names that have not been defined in CSS will render at the bottom of the document,
  stacked and not positioned (appended to `<body>` inside a `<b-toaster>` with class name and ID set
  to the toaster target name). The only default styling the toaster will have is a `z-index` of
  `1100`.
- Avoid using `b-toaster-top-*` toasters together, or `b-toaster-bottom-*` toasters together, at the
  same time in your app as notifications could be obscured/overlap on small screens (i.e. `xs`).

### Prepend and append

Toasts default to prepending themselves to the top of the toasts shown in the specified toaster in
the order they were created. To append new toasts to the bottom, set the `append-toast` prop to
`true`.

### Auto-hide

Change to auto hide delay time via the `auto-hide-delay` prop (value is in milliseconds), which
defaults to `5000` (minimum value `1000`). Or, disable the auto-hide feature completely by setting
the `no-auto-hide` prop to `true`.

When auto-hide is enabled, hovering over the toast will pause the auto-hide timer. When you un-hover
the toast, the auto-hide timer will be resumed. You can disable this feature by setting the
`no-hover-pause` prop to `true`.

### Toast roles

Toasts are rendered with a default `role` attribute of `'alert'` and `aria-live` attribute of
`'assertive'`. For toasts that are meant for a casual notification, set the `is-status` prop to
`true`, which will change the `role` and `aria-live` attributes to `'status'` and `'polite'`
respectively.

For more information, please the the [Accessibility](#accessibility) section below.

### Links

Optionally convert the toast body to a link (`<a>`) or `<router-link>` (or `<nuxt-link>`) via the
`href` and `to` props respectively. When set, the entire toast body becomes a link.

```html
<template>
  <div>
    <b-button @click="toast()">Toast with link</b-button>
  </div>
</template>

<script>
  export default {
    methods: {
      toast() {
        this.$bvToast.toast(`Toast with action link`, {
          href: '#foo',
          title: 'Example'
        })
      }
    }
  }
</script>

<!-- toast-link.vue -->
```

## `<b-toast>` component

When you have a custom component that would like to display just a single toast at a time, use the
`<b-toast>` component. The `<b-toast>` component can be placed anywhere in your custom component or
app, and does not render an element (they render a comment placeholder node which will not affect
layout).

The toast can be made visible via a `v-model` (which is tied to the `visible` prop), or shown using
the component's `show()` and `hide()` instance methods, or via the `this.$bvToast.show(id)` and
`this.$bvToast.hide(id)` methods (requires that a unique ID be set on the `<b-toast>` component).

Toasts, by default will be paced into the `b-toaster-top-right` `<b-toaster>` component. The toaster
specified by the `toaster` prop will be created on demand if it doesn't already exist in document.

You can force a `<b-toast>` to appear in-place in the document by setting the `static` prop to
`true`. you still need to show and hide the toast, but it will not be transported into a toaster
component.

```html
<template>
  <div>
    <b-button @click="$bvToast.show('my-toast')">Show toast</b-button>

    <b-toast id="my-toast" variant="warning" solid>
      <div slot="toast-title" class="d-flex flex-grow-1 align-items-baseline">
        <b-img blank blank-color="#ff5555" class="mr-2" width="12" height="12"></b-img>
        <strong class="mr-auto">Notice!</strong>
        <small class="text-muted mr-2">42 seconds ago</small>
      </div>
      This is the content of the toast.
      It is short and to the point.
    </b-toast>
  </div>
</template>

<!-- toast-component.vue -->
```

### Slots

- `toast-title`: Content to replace the default title element.
- `default`: Content of the toast body

Both slots are optionally scoped with the following scope:

| Method or property | Description                                                                     |
| ------------------ | ------------------------------------------------------------------------------- |
| `hide()`           | Hides the toast when called. Useful if you are providing your own close button. |

Slots are only available when using the `<b-toast>` component.

## `<b-toaster>` target component

The `<b-toaster>` component provides a container where toasts will appear (the _Toaster_). Toasters
require a unique name, and toasts can be targeted to appear in a specific named toaster.

In most cases you will not need to directly use this component, as `<b-toast>` will automatically
insert a `<b-toaster>` component (appended to `<body>`) with the requested toaster name if one is
not found in the document. But sometimes you may want to explicitly place a toaster in your app.

The toaster `name` becomes the ID of the inserted container, and will also be used a class name on
the rendered toaster container.

Toaster positioning and the positioning of toasts inside the toaster is driven completely by CSS
classes (based on the name of the toaster)

The following "built-in" toaster names (and associated styles) are defined in BootstrapVue's custom
SCSS:

- `b-toaster-top-right`
- `b-toaster-top-left`
- `b-toaster-top-center`
- `b-toaster-top-full`
- `b-toaster-bottom-right`
- `b-toaster-bottom-left`
- `b-toaster-bottom-center`
- `b-toaster-bottom-full`

The above toasters place the toasts in a stacked (columnar format), fixed within the viewport
(meaning they will always be in view regardless of viewport scroll position). If there are more
toasts than can fit on the viewport screen, some will be visually hidden offscreen until other
toasts are closed/hidden.

`<b-toast>` uses the `b-toaster-top-right` toaster by default.

**Notes:**

- If a `<b-toaster>` with the same name already exists in document (either auto-created by
  `<b-toast>`, `this.$bvToast.toast()`, or manually placed), then `<b-toaster>` will just render an
  empty `<div>` element and issue a console warning.
- If manually placing a `<b-toaster>` component, make sure it is placed as the last element in
  bottom of your app root element, so that it will be available to all pages in your app.
- Toasters that get destroyed will be auto re-created if a new toast targeted for the toaster name
  is shown.
- In the majority of use cases, you should not need to manually place/create a `<b-toaster>`
  component in your app, as they will be auto generated on demand if needed. But if you need to
  override any of the toaster default settings, ensure that you place the toaster in your app in a
  location that will not be destroyed due to changes in the route.

## Advanced usage

When using the `this.$bvToast.toast(...)` method for generating toasts, you may want the toast
content to be more than just a string message. As mentioned in the
[Toasts on demand](#toasts-on-demand) section above, you can pass arrays of `vNodes` as the message
and title for more complex content.

Remember to keep toast content simple and to the point. Avoid placing interactive components or
elements inside toasts, as this can cause issues for users of assistive technologies. Refer to the
[Accessibility](#accessibility) section below.

Below is an example of using Vue's
[`this.$createElement()`](https://vuejs.org/v2/guide/render-function.html#The-Virtual-DOM) method
for generating more complex toast content:

```html
<template>
  <div>
    <b-button @click="popToast">Show Toast with custom content</b-button>
  </div>
</template>

<script>
  export default {
    data() {
      return {
        count: 0
      }
    },
    methods: {
      popToast() {
        // Use a shorter name for this.$createElement
        const h = this.$createElement
        // Increment the toast count
        this.count++
        // Create the message
        const vNodesMsg = h(
          'p',
          { class: ['text-center', 'mb-0'] },
          [
            h('b-spinner', { props: { type: 'grow', small: true } }),
            ' Flashy ',
            h('strong', {}, 'toast'),
            ` message #${this.count} `,
            h('b-spinner', { props: { type: 'grow', small: true } })
          ]
        )
        // Create the title
        const vNodesTitle = h(
          'div',
          { class: ['d-flex', 'flex-grow-1', 'align-items-baseline', 'mr-2'] },
          [
            h('strong', { class: 'mr-2' }, 'The Title'),
            h('small', { class: 'ml-auto text-italics' }, '5 minutes ago')
          ]
        )
        // Pass the vNodes as an array for message and title
        this.$bvToast.toast([vNodesMsg], {
          title: [vNodesTitle],
          solid: true,
          variant: 'info'
        })
      }
    }
 }
</script>

<!-- toasts-advanced.vue -->
```

## Accessibility

Toasts are intended to be **small interruptions** to your visitors or users, so to help those with
screen readers and similar assistive technologies, toasts are wrapped in an aria-live region.
Changes to live regions (such as injecting/updating a toast component) are automatically announced
by screen readers without needing to move the user’s focus or otherwise interrupt the user.
Additionally, `aria-atomic="true"` is automatically set to ensure that the entire toast is always
announced as a single (atomic) unit, rather than announcing what was changed (which could lead to
problems if you only update part of the toast’s content, or if displaying the same toast content at
a later point in time).

### Accessibility tips

Typically, toast messages should display one or two-line non-critical messages that **do not**
require user interaction. Without taking extra steps, toasts can have numerous accessibility issues
that can impact both people with and without disabilities. The following list, while not complete,
provides general guidelines when using toasts.

- If the information needed is important for the process, e.g. for a list of errors in a form, then
  use the [`<b-alert>`](/docs/components/alert) component instead of `<b-toast>`.
- `<b-toast>`, by default, sets the attributes `role` to `'alert'` and `aria-live` to `'assertive'`.
  If it’s an important message like an error, this default setting is appropriate, otherwise set the
  prop `is-status` to `true` which will change the attributes `role` to `'status'` and `aria-live`
  to `'polite'`.
- Avoid popping up a toast message on page load. Performing unexpected actions on page load is very
  confusing to screen reader users. If a toast is needed on page load or route change, delay showing
  the toast by several seconds so that the screen reader will finishing announcing information about
  the current page without interruption by a the toast.
- When setting prop `auto-hide` to `false`, you must have a close button to allow users to dismiss
  the toast. If you have also set prop `no-close-button` to true, you must provide your own close
  button or dismiss the toast by some other means. Toasts have a tab index of `0` so that they can
  be reached by keyboard-only users.
- Avoid initiating many toasts in quick succession, as screen readers may interrupt reading the
  current toast and announce the new toast, causing the context of the previous toast to be missed.
- For toasts with long textual content, adjust the `auto-hide-delay` to a larger timout, to allow
  users time to read the content of the toast. A good length of time to keep messages up is 4
  seconds plus 1 extra second for every 100 words, rounding up. This is approximately how fast the
  average person reads. That means the shortest default that should be used as a best practice is 5
  seconds (5000ms). In addition to a reasonable default timeout, you could also allow the user to
  choose how long they want toasts to stay up for. Most people inherently understand whether they
  are fast or slow readers. Having a profile setting that is part of the user login will allow slow
  readers to pick a longer time if the messages are going away too fast, and fast readers to pick a
  short time if the messages are staying up too long.
- To account for memory loss and distraction as well as disability-related issues such as ADHD, a
  best practice would be to implement a location where users can refer to a list of past toast
  messages which have been shown. Preferably this list should be sortable, with the default being
  chronological.

### Internet Explorer screen reader support

Unfortunately, IE 11 when used with [NVDA](https://github.com/nvaccess/nvda) or
[JAWS](http://www.freedomscientific.com/products/software/jaws/) screen readers, will not properly
announce/voice toasts when they appear. If you have a large non-sighted user-base using IE 11, you
may want to create an additional off-screen `aria-live` region for IE 11 browsers only (created on
page load) where copies of toast message text are placed dynamically, in addition to displaying
toasts.

<!-- Component reference added automatically from component package.json -->