Form Textarea
Create multi-line text inputs with support for auto height sizing, minimum and maximum number of rows, and contextual states.
<template>
<div>
<b-form-textarea
id="textarea"
v-model="text"
placeholder="Enter something..."
rows="3"
max-rows="6"
></b-form-textarea>
<pre class="mt-3 mb-0">{{ text }}</pre>
</div>
</template>
<script>
export default {
data() {
return {
text: ''
}
}
}
</script>
<!-- b-form-textarea.vue -->
Control sizing
Set text height using the size
prop to sm
or lg
for small or large respectively.
To control width, place the input inside standard Bootstrap grid column.
<b-container fluid>
<b-row>
<b-col sm="2">
<label for="textarea-small">Small:</label>
</b-col>
<b-col sm="10">
<b-form-textarea
id="textarea-small"
size="sm"
placeholder="Small textarea"
></b-form-textarea>
</b-col>
</b-row>
<b-row class="mt-2">
<b-col sm="2">
<label for="textarea-default">Default:</label>
</b-col>
<b-col sm="10">
<b-form-textarea
id="textarea-default"
placeholder="Default textarea"
></b-form-textarea>
</b-col>
</b-row>
<b-row class="mt-2">
<b-col sm="2">
<label for="textarea-large">Large:</label>
</b-col>
<b-col sm="10">
<b-form-textarea
id="textarea-large"
size="lg"
placeholder="Large textarea"
></b-form-textarea>
</b-col>
</b-row>
</b-container>
<!-- b-form-textarea-sizes.vue -->
Displayed rows
To set the height of <b-form-textarea>
, set the rows
prop to the desired number of rows. If no
value is provided to rows
, then it will default to 2
(the browser default and minimum acceptable
value). Setting it to null or a value below 2 will result in the default of 2
being used.
<div>
<b-form-textarea
id="textarea-rows"
placeholder="Tall textarea"
rows="8"
></b-form-textarea>
</div>
<!-- b-form-textarea-rows.vue -->
Disable resize handle
Some web browsers will allow the user to re-size the height of the textarea. To disable this
feature, set the no-resize
prop to true
.
<div>
<b-form-textarea
id="textarea-no-resize"
placeholder="Fixed height textarea"
rows="3"
no-resize
></b-form-textarea>
</div>
<!-- b-form-textarea-no-resize.vue -->
Auto height
<b-form-textarea>
can also automatically adjust its height (text rows) to fit the content, even as
the user enters or deletes text. The height of the textarea will either grow or shrink to fit the
content (grow to a maximum of max-rows
or shrink to a minimum of rows
).
To set the initial minimum height (in rows), set the rows
prop to the desired number of lines (or
leave it at the default of 2
), And then set maximum rows that the text area will grow to (before
showing a scrollbar) by setting the max-rows
prop to the maximum number of lines of text.
To make the height sticky
(i.e. never shrink), set the no-auto-shrink
prop to true
. The
no-auto-shrink
props has no effect if max-rows
is not set or is equal to or less than rows
.
Note that the resize handle of the textarea (if supported by the browser) will automatically be disabled in auto-height mode.
<b-container fluid>
<b-row>
<b-col sm="2">
<label for="textarea-auto-height">Auto height:</label>
</b-col>
<b-col sm="10">
<b-form-textarea
id="textarea-auto-height"
placeholder="Auto height textarea"
rows="3"
max-rows="8"
></b-form-textarea>
</b-col>
</b-row>
<b-row class="mt-2">
<b-col sm="2">
<label for="textarea-no-auto-shrink">No auto-shrink:</label>
</b-col>
<b-col sm="10">
<b-form-textarea
id="textarea-no-auto-shrink"
placeholder="Auto height (no-shrink) textarea"
rows="3"
max-rows="8"
no-auto-shrink
></b-form-textarea>
</b-col>
</b-row>
</b-container>
<!-- b-form-textarea-auto-height.vue -->
Auto height implementation note
Auto-height works by computing the resulting height via CSS queries, hence the input has to be in
document (DOM) and visible (not hidden via display: none
). Initial height is computed on mount. If
the browser client supports <code>IntersectionObserver</code>
(either natively or via a polyfill), <b-form-textarea>
will take advantage of this to
determine when the textarea becomes visible and will then compute the height. Refer to the
Browser support section on the getting started page.
Contextual states
Bootstrap includes validation styles for valid
and invalid
states on most form controls.
Generally speaking, you'll want to use a particular state for specific types of feedback:
false
(denotes invalid state) is great for when there's a blocking or required field. A user must fill in this field properly to submit the form.true
(denotes valid state) is ideal for situations when you have per-field validation throughout a form and want to encourage a user through the rest of the fields.null
Displays no validation state (neither valid nor invalid)
To apply one of the contextual state icons on <b-form-textarea>
, set the state
prop to false
(for invalid), true
(for valid), or null
(no validation state).
<template>
<div>
<b-form-textarea
id="textarea-state"
v-model="text"
:state="text.length >= 10"
placeholder="Enter at least 10 characters"
rows="3"
></b-form-textarea>
</div>
</template>
<script>
export default {
data() {
return {
text: ''
}
}
}
</script>
<!-- b-form-textarea-state.vue -->
Conveying contextual state to assistive technologies and colorblind users
Using these contextual states to denote the state of a form control only provides a visual, color-based indication, which will not be conveyed to users of assistive technologies - such as screen readers - or to colorblind users.
Ensure that an alternative indication of state is also provided. For instance, you could include a
hint about state in the form control's <label>
text itself, or by providing an additional help
text block.
aria-invalid
attribute
When <b-form-textarea>
has an invalid contextual state (i.e. state is false
) you may also want
to set the prop aria-invalid
to true
, or one of the supported values:
false
: No errors (default)true
or'true'
: The value has failed validation.'grammar'
: A grammatical error has been detected.'spelling'
A spelling error has been detected.
If the state
prop is set to false
, and the aria-invalid
prop is not explicitly set,
<b-form-textarea>
will automatically set the aria-invalid
attribute to 'true'
.
Formatter support
<b-form-textarea>
optionally supports formatting by passing a function reference to the
formatter
prop.
Formatting (when a formatter function is supplied) occurs when the control's native input
and
change
events fire. You can use the boolean prop lazy-formatter
to restrict the formatter
function to being called on the control's native blur
event.
The formatter
function receives two arguments: the raw value
of the input element, and the
native event
object that triggered the format (if available).
The formatter
function should return the formatted value as a string.
Formatting does not occur if a formatter
is not provided.
<template>
<div>
<b-form-group
label="Textarea with formatter (on input)"
label-for="textarea-formatter"
description="We will convert your text to lowercase instantly"
class="mb-0"
>
<b-form-textarea
id="textarea-formatter"
v-model="text1"
placeholder="Enter your text"
:formatter="formatter"
></b-form-textarea>
</b-form-group>
<p style="white-space: pre-line"><b>Value:</b> {{ text1 }}</p>
<b-form-group
label="Textarea with lazy formatter (on blur)"
label-for="textarea-lazy"
description="This one is a little lazy!"
class="mb-0"
>
<b-form-textarea
id="textarea-lazy"
v-model="text2"
placeholder="Enter your text"
lazy-formatter
:formatter="formatter"
></b-form-textarea>
</b-form-group>
<p class="mb-0" style="white-space: pre-line"><b>Value:</b> {{ text2 }}</p>
</div>
</template>
<script>
export default {
data() {
return {
text1: '',
text2: ''
}
},
methods: {
formatter(value) {
return value.toLowerCase()
}
}
}
</script>
<!-- b-form-textarea-formatter.vue -->
Note: With non-lazy formatting, if the cursor is not at the end of the input value, the cursor
may jump to the end after a character is typed. You can use the provided event object and the
event.target
to access the native input's selection methods and properties to control where the
insertion point is. This is left as an exercise for the reader.
Readonly plain text
If you want to have <b-form-textarea readonly>
elements in your form styled as plain text, set the
plaintext
prop (no need to set readonly
as it will be set automatically) to remove the default
form field styling and preserve the correct text size, margin, padding and height.
<template>
<div>
<b-form-textarea id="textarea-plaintext" plaintext :value="text"></b-form-textarea>
</div>
</template>
<script>
export default {
data() {
return {
text: "This is some text.\nIt is read only and doesn't look like an input."
}
}
}
</script>
<!-- b-form-textarea-plaintext.vue -->
v-model
modifiers
Vue does not officially support .lazy
, .trim
, and .number
modifiers on the v-model
of custom
component based inputs, and may generate a bad user experience. Avoid using Vue's native modifiers.
To get around this, <b-form-textarea>
has three boolean props trim
, number
, and lazy
which
emulate the native Vue v-model
modifiers .trim
and .number
and .lazy
respectively. The
lazy
prop will update the v-model on change
/blur
events.
Notes:
- The
number
prop takes precedence over thetrim
prop (i.e.trim
will have no effect whennumber
is set). - When using the
number
prop, and if the value can be parsed as a number (viaparseFloat
) it will return a value of typeNumber
to thev-model
, otherwise the original input value is returned as typeString
. This is the same behaviour as the native.number
modifier. - The
trim
andnumber
modifier props do not affect the value returned by theinput
orchange
events. These events will always return the string value of the content of<textarea>
after optional formatting (which may not match the value returned via thev-model
update
event, which handles the modifiers).
Debounce support
As an alternative to the lazy
modifier prop, <b-form-textarea>
optionally supports debouncing
user input, updating the v-model
after a period of idle time from when the last character was
entered by the user (or a change
event occurs). If the user enters a new character (or deletes
characters) before the idle timeout expires, the timeout is re-started.
To enable debouncing, set the prop debounce
to any integer greater than zero. The value is
specified in milliseconds. Setting debounce
to 0
will disable debouncing.
Note: debouncing will not occur if the lazy
prop is set.
<template>
<div>
<b-form-textarea v-model="value" debounce="500" rows="3" max-rows="5"></b-form-textarea>
<pre class="mt-2 mb-0">{{ value }}</pre>
</div>
</template>
<script>
export default {
data() {
return {
value: ''
}
}
}
</script>
<!-- b-form-textarea-debounce.vue -->
Autofocus
When the autofocus
prop is set on <b-form-textarea>
, the textarea will be auto-focused when it
is inserted (i.e. mounted) into the document or re-activated when inside a Vue <keep-alive>
component. Note that this prop does not set the autofocus
attribute on the textarea, nor can
it tell when the textarea becomes visible.
Native and custom events
All native events (other than the custom input
and change
events) are supported, without the
need for the .native
modifier.
The custom input
and change
events receive a single argument of the current value
(after any
formatting has been applied), and are triggered by user interaction.
The custom update
event is passed the input value, and is emitted whenever the v-model
needs
updating (it is emitted before input
, change
. and blur
as needed).
You can always access the native input
and change
events by using the .native
modifier.
Exposed input properties and methods
<b-form-textarea>
exposes several of the native input element's properties and methods on the
component reference (i.e. assign a ref
to your <b-form-textarea ref="foo" ...>
and use
this.$refs['foo'].propertyName
or this.$refs['foo'].methodName(...)
).
Input properties
Property | Notes |
---|---|
.selectionStart |
Read/Write |
.selectionEnd |
Read/Write |
.selectionDirection |
Read/Write |
.validity |
Read only |
.validationMessage |
Read only |
.willValidate |
Read only |
Input methods
Method | Notes |
---|---|
.focus() |
Focus the input |
.blur() |
Remove focus from the input |
.select() |
Selects all text within the input |
.setSelectionRange() |
|
.setRangeText() |
|
.setCustomValidity() |
|
.checkValidity() |
|
.reportValidity() |
Refer to https://developer.mozilla.org/en-US/docs/Web/API/HTMLInputElement for more information on these methods and properties. Support will vary based on input type.
<!-- Component reference added automatically from component package.json -->