<text-expander> element

Activates a suggestion menu to expand text snippets as you type.

Installation

$ npm install --save @github/text-expander-element

Usage

Script

Import as ES modules:

import '@github/text-expander-element'

With a script tag:

<script type="module" src="./node_modules/@github/text-expander-element/dist/bundle.js">

Markup

<text-expander keys=": @ #" multiword="#">
  <textarea></textarea>
</text-expander>

Attributes

• keys is a space separated list of menu activation keys
• multiword defines whether the expansion should use several words or not
  • you can provide a space separated list of activation keys that should support multi-word matching
• suffix is a string that is appended to the value during expansion, default is a single space character

Events

text-expander-change is fired when a key is matched. In event.detail you can find:

• key: The matched key; for example: :.
• text: The matched text; for example: cat, for :cat.
  • If the key is specified in the multiword attribute then the matched text can contain multiple words; for example cat and dog for :cat and dog.
• provide: A function to be called when you have the menu results. Takes a Promise with {matched: boolean, fragment: HTMLElement} where matched tells the element whether a suggestion is available, and fragment is the menu content to be displayed on the page.

const expander = document.querySelector('text-expander')

expander.addEventListener('text-expander-change', function(event) {
  const {key, provide, text} = event.detail
  if (key !== ':') return

  const suggestions = document.querySelector('.emoji-suggestions').cloneNode(true)
  suggestions.hidden = false
  for (const suggestion of suggestions.children) {
    if (!suggestion.textContent.match(text)) {
      suggestion.remove()
    }
  }
  provide(Promise.resolve({matched: suggestions.childElementCount > 0, fragment: suggestions}))
})

The returned fragment should be consisted of filtered [role=option] items to be selected. For example:

<ul class="emoji-suggestions" hidden>
  <li role="option" data-value="🐈">🐈 :cat2:</li>
  <li role="option" data-value="🐕">🐕 :dog:</li>
</ul>

text-expander-value is fired when an item is selected. In event.detail you can find:

• key: The matched key; for example: :.
• item: The selected item. This would be one of the [role=option]. Use this to work out the value.
• value: A null value placeholder to replace the query. To replace the text query, simply re-assign this value.
• continue: A boolean value to specify whether to continue autocompletion after inserting a value. Defaults to false. If set to true, will not add a space after inserted value and will keep firing the text-expander-change event.

const expander = document.querySelector('text-expander')

expander.addEventListener('text-expander-value', function(event) {
  const {key, item}  = event.detail
  if (key === ':') {
    event.detail.value = item.getAttribute('data-value')
  }
})

text-expander-committed is fired after the underlying input value has been updated in the DOM. In event.detail you can find:

• input: The HTMLInputElement or HTMLTextAreaElement that just had value changes committed to the DOM.

const expander = document.querySelector('text-expander')

expander.addEventListener('text-expander-committed', function(event) {
  const {input}  = event.detail
})

text-expander-activate is fired just after the menu has been assigned and appended to the DOM, and just before it is about to be positioned near the text to expand. This is useful for assigning classes or calling imperative methods to show the menu, such as .showPopover().

text-expander-deactivate is fired just before the menu is going to be unassigned and removed from the DOM. This is useful for removing classes or running cleanup like removing from caches.

Browser support

Browsers without native custom element support require a polyfill.

• Chrome
• Firefox
• Safari
• Microsoft Edge

Development

npm install
npm test

License

Distributed under the MIT license. See LICENSE for details.