Overview
This text input component is useful in situations where you want to ask the user to enter as much text as they want, but don't want to take up a lot of room on the page.
Note: This component uses WrappedStandardElement
to wrap a standard <textarea>
element. This allows it to provide all
standard HTMLTextAreaElement
properties, methods, and events, in addition
to those specifically listed in the AutoSizeTextarea
API.
API
Ancestry: AutoSizeTextarea → WrappedStandardElement → ReactiveElement → HTMLElement
Built with mixins AttributeMarshallingMixin, DelegateFocusMixin, FormElementMixin, ReactiveMixin, ShadowTemplateMixin, and SlotContentMixin.
The element defines the following shadow parts:
inner
: the inner standard HTML element
extends property
The tag name of the standard HTML element extended by this class.
Defined by WrappedStandardElement
form property
The ID of the form
element with which this element is associated,
or null
if the element is not associated with any form. This is provided
for consistency with the native HTML
form
property.
Type: string
Defined by FormElementMixin
get Inner Property(name) method
Return the value of the named property on the inner standard element.
Parameters:
- name:
string
–
Returns: any
Defined by WrappedStandardElement
inner property
Returns a reference to the inner standard HTML element!
Type: HTMLElement
Defined by WrappedStandardElement
input event
Raised when the user changes the element's text content.
This is the standard input
event; the component does not do any work to
raise it. It is documented here to let people know it is available to
detect when the user edits the content.
[internal.content Slot] property
See internal.contentSlot.
Defined by SlotContentMixin
[internal.default State] property
The default state for the component. This can be extended by mixins and classes to provide additional default state.
Type: State
Defined by ReactiveMixin
[internal.delegates Focus] property
Returns true if the component is delegating its focus.
A component using DelegateFocusMixin
will always have this property be
true unless a class takes measures to override it.
Type: boolean
Default: true
Defined by DelegateFocusMixin
[internal.ids] property
A convenient shortcut for looking up an element by ID in the component's Shadow DOM subtree.
Example: if component's template contains a shadow element <button
id="foo">
, you can use the reference this[internal.ids].foo
to obtain
the corresponding button in the component instance's shadow tree. The
ids
property is simply a shorthand for getElementById
, so
this[internal.ids].foo
is the same as
this.shadowRoot.getElementById('foo')
.
Type: object
Defined by ShadowTemplateMixin
[internal.render](changed) method
Render the indicated changes in state to the DOM.
The default implementation of this method does nothing. Override this method in your component to update your component's host element and any shadow elements to reflect the component's new state. See the rendering example.
Be sure to call super
in your method implementation so that your
component's base classes and mixins have a chance to perform their own
render work.
Parameters:
- changed:
object
– dictionary of flags indicating which state members have changed since the last render
Defined by ReactiveMixin
[internal.render Changes]() method
Render any pending component changes to the DOM.
This method does nothing if the state has not changed since the last render call.
ReactiveMixin will invoke this method following a setState
call;
you should not need to invoke this method yourself.
This method invokes all internal render methods, then invokes
componentDidMount
(for first render) or componentDidUpdate
(for
subsequent renders).
Defined by ReactiveMixin
[internal.set State](changes) method
Update the component's state by merging the specified changes on top of the existing state. If the component is connected to the document, and the new state has changed, this returns a promise to asynchronously render the component. Otherwise, this returns a resolved promise.
Parameters:
- changes:
object
– the changes to apply to the element's state
Returns: Promise
- resolves when the new state has been rendered
Defined by ReactiveMixin
[internal.state] property
The component's current state.
The returned state object is immutable. To update it, invoke
internal.setState
.
It's extremely useful to be able to inspect component state while
debugging. If you append ?elixdebug=true
to a page's URL, then
ReactiveMixin will conditionally expose a public state
property
that returns the component's state. You can then access the state
in your browser's debug console.
Type: State
Defined by ReactiveMixin
[internal.template] property
The template copied into the shadow tree of new instances of this element.
The default value of this property is a template that includes an instance
the standard element being wrapped, with a <slot>
element inside that
to pick up the element's light DOM content. For example, if you wrap an
<a>
element, then the default template will look like:
<template>
<style>
:host {
display: inline-block;
}
</style>
<a id="inner">
<slot></slot>
</a>
</template>
The display
styling applied to the host will be block
for elements that
are block elements by default, and inline-block
(not inline
) for other
elements.
If you'd like the template to include other elements, then override this property and return a template of your own. The template should include an instance of the standard HTML element you are wrapping, and the ID of that element should be "inner".
Type: string|HTMLTemplateElement
Defined by WrappedStandardElement
minimum Rows property
Determines the minimum number of rows shown. This is similar to the rows attribute on a standard textarea, but because this element can grow, is expressed as a minimum rather than a fixed number.
By default, this property is 1, so when empty, the text area will be a single line tall. That's efficient in terms of the space it consumes, but until the user interacts with the element, they may not realize they can enter multiple lines of text. Setting the property to a value higher than 1 will signal to the user that they can enter multiple lines of a text.
By setting this property, you can also communicate to the user some sense of how much text you're expecting them to provide. For example, on a feedback form, asking the user to enter their feedback in a single-line text box implies you don't really want them to enter much text — even if the text box will grow when they type. By setting this to a value like, say, 10 rows, you can signal that you're fully expecting them to enter more text.
Type: number
Default: 1
name property
The name of the form field that will be filled with this element's
value
. This is an analogue of the standard HTML
name
property.
Type: string
Defined by FormElementMixin
set Inner Property(name, value) method
Set the named property on the inner standard element.
Parameters:
- name:
string
– - value:
any
–
Defined by WrappedStandardElement
type property
The "type" of the form field, provided for consistency with the native HTML type property. The value of this property will be the same as the HTML tag name registered for the custom element.
Type: string
Defined by FormElementMixin
value property
The text currently shown in the textarea.
Note that the text shown in the textarea can also be updated by changing the element's innerHTML/textContent. However, if the value property is explicitly set, that will override the innerHTML/textContent.
Type: string
wrap(extendsTag) static method
Creates a class that wraps a standard HTML element.
Note that the resulting class is a subclass of WrappedStandardElement, not
the standard class being wrapped. E.g., if you call
WrappedStandardElement.wrap('a')
, you will get a class whose shadow tree
will include an anchor element, but the class will not inherit from
HTMLAnchorElement.
Parameters:
- extendsTag:
string
– the standard HTML element tag to extend
Defined by WrappedStandardElement