@material/mwc-textarea
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    0.25.3 • Public • Published

    <mwc-textarea> Published on npm

    IMPORTANT: The Material Web Components are a work in progress and subject to major changes until 1.0 release.

    Text areas let users enter and edit text.

    Material Design Guidelines: text areas

    Demo

    Installation

    npm install @material/mwc-textarea

    NOTE: The Material Web Components are distributed as ES2017 JavaScript Modules, and use the Custom Elements API. They are compatible with all modern browsers including Chrome, Firefox, Safari, Edge, and IE11, but an additional tooling step is required to resolve bare module specifiers, as well as transpilation and polyfills for IE11. See here for detailed instructions.

    Example usage

    Standard

    <mwc-textarea label="My Textarea"></mwc-textarea>
    
    <script type="module">
      import '@material/mwc-textarea';
    </script>

    Helper Text

    <mwc-textarea label="My Textarea" helper="Helper Text"></mwc-textarea>

    Primary Color

    <style>
      mwc-textarea {
        --mdc-theme-primary: green;
      }
    </style>
    
    <mwc-textarea
        label="My Textarea"
        required>
    </mwc-textarea>

    Variants

    Outlined

    <mwc-textarea
        outlined
        label="My Textarea">
    </mwc-textarea>

    Shaped

    <style>
      mwc-textarea.rounded {
        --mdc-shape-small: 28px;
      }
    </style>
    
    <mwc-textarea
        class="rounded"
        label="My Textarea"
        outlined>
    </mwc-textarea>

    API

    Properties/Attributes

    Name Type Description
    rows number Sets number of visible text lines.
    cols number Sets the visible width of the textarea.
    value string The input control's value.
    type TextFieldType* A string specifying the type of control to render.
    label string Sets floating label value.
    placeholder string Sets disappearing input placeholder.
    icon string Leading icon to display in input. See mwc-icon.
    iconTrailing string Trailing icon to display in input. See mwc-icon.
    disabled boolean Whether or not the input should be disabled.
    charCounter boolean|TextAreaCharCounter** Note: requires maxLength to be set. Display character counter with max length. Textareas may display an "external" or "internal" charCounter. When true, textareas display an external character counter by default.
    outlined boolean Whether or not to show the material outlined variant.
    helper string Helper text to display below the input. Display default only when focused.
    helperPersistent boolean Always show the helper text despite focus.
    required boolean Displays error state if value is empty and input is blurred.
    maxLength number Maximum length input to accept.
    validationMessage string Message to show in the error color when the textarea is invalid. (Helper text will not be visible)
    validity ValidityState (readonly) The ValidityState of the textfield.
    willValidate boolean (readonly) HTMLInputElement.prototype.willValidate
    validityTransform ValidityTransform***|null Callback called before each validation check. See the validation section for more details.
    validateOnInitialRender boolean Runs validation check on initial render.
    name string Sets the name attribute on the internal textarea.***

    * TextFieldType is exported by mwc-textarea and mwc-textarea-base.

    type TextFieldType = 'text'|'search'|'tel'|'url'|'email'|'password'|
        'date'|'month'|'week'|'time'|'datetime-local'|'number'|'color';

    ** TextAreaCharCounter is exported by mwc-textarea.

    type TextAreaCharCounter = 'external'|'internal';
    
    \*\*\* `ValidityTransform` is not exported. See the [validation section](#Validation) for more details.
    ```ts
    type ValidityTransform = (value: string, nativeValidity: ValidityState) => Partial<ValidityState>

    *** The name property should only be used for browser autofill as webcomponent form participation does not currently consider the name attribute. See #289.

    Methods

    Name Description
    checkValidity() => boolean Returns true if the textarea passes validity checks. Returns false and fires an invalid event on the textarea otherwise.
    reportValidity() => boolean Runs checkValidity() method, and if it returns false, then it reports to the user that the input is invalid.
    setCustomValidity(message:string) => void Sets a custom validity message (also overwrites validationMessage). If this message is not the empty string, then the element is suffering from a custom validity error and does not validate.
    layout() => Promise<void> Re-calculate layout. If a textarea is styled with display:none before it is first rendered, and it has a label that is floating, then you must call layout() the first time you remove display:none, or else the notch surrounding the label will not render correctly.

    CSS Custom Properties

    Inherits CSS Custom properties from:

    Name Default Description
    --mdc-text-area-filled-border-radius 4px 4px 0 0 Border radius of the standard / filled textarea's background filling.
    --mdc-text-area-outlined-idle-border-color rgba(0, 0, 0, 0.38) Color of the outlined textarea's outline when idle.
    --mdc-text-area-outlined-hover-border-color rgba(0, 0, 0, 0.87) Color of the outlined textarea's outline when hovering.
    --mdc-text-area-outlined-disabled-border-color rgba(0, 0, 0, 0.06) Color of the outlined textarea's outline when disabled.

    Global Custom Properties

    This component exposes the following global theming custom properties.

    Name Description
    --mdc-theme-primary Color when active of the underline ripple, the outline, and the caret.
    --mdc-theme-error Color when errored of the underline, the outline, the caret, and the icons.
    --mdc-typography-subtitle1-<PROPERTY> Styles the typography of the texarea, excluding line-height.

    Validation

    <mwc-textarea> follows the basic <input> constraint validation model. It exposes:

    • required
    • maxLength
    • validity
    • willValidate
    • checkValidity()
    • reportValidity()
    • setCustomValidity(message)

    Additionally, it implements more features such as:

    • validationMessage
    • validateOnInitialRender
    • and validityTransform

    By default, <mwc-textarea> will report validation on blur.

    Custom validation logic

    The validityTransform property is a function that can be set on <mwc-textarea> to implement custom validation logic that transforms the ValidityState of the input control. The type of a ValidityTransform is the following:

    (value: string, nativeValidity: ValidityState) => Partial<ValidityState>

    Where value is the new value in the textarea to be validated and nativeValidity is an interface of ValidityState of the native input control. For example:

    <mwc-textarea
        id="my-textarea"
        maxlength="5"
        value="doggos">
    </mwc-textarea>
    <script>
      const textarea = document.querySelector('#my-textarea');
      textarea.validityTransform = (newValue, nativeValidity) => {
        if (!nativeValidity.valid) {
          if (nativeValidity.tooLong) {
            const hasDog = newValue.includes('dog');
            // changes to make to the nativeValidity
            return {
              valid: hasDog,
              tooLong: !hasDog;
            };
          } else {
            // no changes
            return {};
          }
        } else {
          const isValid = someExpensiveOperation(newValue);
          // changes to make to the native validity
          return {
            valid: isValid,
            // or whatever type of ValidityState prop you would like to set (if any)
            customError: !isValid,
          };
        }
      }
    </script>

    In this example we first check the native validity which is invalid due to the maxlength (the value is doggos which is a string longer than 5). The value includes dog, thus we make it valid and undo the tooLong error in the ValidityState by returning a Partial<ValidityState> that indicates what to change in the initial validity.

    In this example, we also skip an expensive validity check by short-circuiting the validation by checking the native validation.

    Note: the UI will only update as valid / invalid by checking the valid property of the transformed ValidityState.

    Additional references

    Install

    npm i @material/mwc-textarea

    DownloadsWeekly Downloads

    6,212

    Version

    0.25.3

    License

    Apache-2.0

    Unpacked Size

    39.4 kB

    Total Files

    13

    Last publish

    Collaborators

    • yefim
    • abhiomkar
    • azakus
    • bicknellr
    • material-admin
    • aprigogin
    • patrickrodee
    • aomarks
    • emarquez
    • allanchen
    • esgonzalez
    • asyncliz
    • candysonya
    • ssuarez
    • taylorv