Binding to 'input' and 'change' events too early?

Stretchy

Form element autosizing, the way it should be!

Features

Handles multiple types of form controls Textareas? Inputs? Select menus? You name it!
Tiny footprint Less than 1.5KB minified and gzipped!
Automatically accounts for newly added controls via mutation observers
Restrict form controls by a selector …or don’t and autosize all your form controls!
Completely standalone no jQuery or other dependencies
Plays well with existing HTML/CSS Follows placeholders, styling, min/max-width/height constraints, transitions
No JS knowledge required Everything can be configured just via HTML!
Works in all modern browsers (v1 even works in old browsers)
Written in ESM Available in ESM, CJS, and good ol' globals
Works in Shadow DOM Use it in your web components!

Usage

Good ol’ `<script>` element

This method is optimal if you don't need much control, and would rather avoid writing any JS.

Just include the script anywhere in the page:

<script src="https://stretchy.verou.me/dist/stretchy.iife.min.js" async></script>

If you include Stretchy this way it will run automatically and you don’t need to do anything else (unless you want to customize which elements it applies to).

ESM (v2.0.0+)

This method is ideal if you are including Stretchy as a dependency on a larger project and want to prevent any side effects.

import * as Stretchy from "https://stretchy.verou.me/dist/stretchy.min.js";
Stretchy.init();

CommonJS (v2.0.0+)

A CommonJS build is also available. require("stretchy") should work on Node.

Local files

All three of the above methods can be used with your own local files as well. You can download Stretchy here.

npm works like you’d expect too:

npm install stretchy

Which elements does Stretchy resize?

By default, Stretchy resizes all <textarea>s, <select> menus with no size attribute and <input> elements that are text fields (e.g. with no type attribute, or with one equal to text, tel, email, url).

To limit that set further you can set an additional filter, via a CSS selector. There are two ways to specify a filter: via HTML attributes (if you'd prefer to avoid writing JS) or via JS.

Via HTML attributes:

Use the data-stretchy-filter attribute, on any element. Note that this means you can use the attribute on the <script> element that calls Stretchy itself, in which case you can also shorten its name to data-filter.

For example, to restrict it to elements that either have the foo class or are inside another element that does, you could use data-stretchy-filter=".foo, .foo *" on an element or call Stretchy like this:

<script src="stretchy.min.js" data-filter=".foo, .foo *" async></script>

If you specify the data-stretchy-filter attribute on multiple elements, the last value (in source order) wins. data-filter directly on Stretchy’s <script> element takes priority over any data-stretchy-filter declaration.

Via JS

If you want to avoid modifying the markup, you can use JavaScript instead:

Stretchy.selectors.filter = ".foo, .foo *";

Note that if you are including Stretchy via a <script> element, it will run as soon as the document is ready, which may be before you’ve set a filter. You need to ensure that line runs after Stretchy has loaded (so that the Stretchy object is available) and before the DOM is ready. To avoid this hassle, I'd recommend using attributes to set the filter if you include Stretchy that way, or including Stretchy as a module if you want to customize its settings via JS.

JavaScript API

Stretchy has a spartan API, since in most cases you don’t need to call it at all. Stretchy works via event delegation and detects new elements via mutation observers, so you do not need to call any API methods for adding new elements via scripting (e.g. AJAX).

If needed, these are Stretchy’s API methods:

Property or Method	Description
`init([root])`	Resize controls inside a given element, and monitor for changes. `root` can be any `Node`, including Shadow roots.
`resize(element)`	Autosize one element based on its content. Note that this does not set up any event listeners, it just calculates and sets the right dimension (width or height, depending on the type of control) once.
`resizeAll([elements \| selector, [root]])`	Apply `Stretchy.resize()` to a collection of elements, or all Stretchy is set to apply to, if no argument is provided.
`resizes(element)`	Can Stretchy be used on this particular element? (checks if element is in the DOM, if it's of the right type and if it matches the selector filter provided by `data-stretchy-selector`, if the attribute is set.
`selectors.base`	CSS selector to tell Stretchy which elements can be resized. Defaults to `input, select, textarea`. Main use case for modifying this is in case you have a custom element that behaves like these and want Stretchy to stop ignoring it. If you just want to filter which elements Stetchy resizes, use `filter` below.
`selectors.filter`	CSS selector that elements need to match to be resized.
`active`	Boolean. Set to `false` to temporarily disable Stretchy globally.`

Browser support

All modern browsers. For details, see .browserslistrc

v1 Browser Support Notes

Stretchy v1 worked in Chrome, FF 3.6, IE9, Opera, Safari, Android & more.

On browsers that do not support mutation observers, you have to manually call Stretchy.resize() on new elements.
IE has an issue with <input> elements, due to it misreporting scrollWidth. If this matters to you, you can use this polyfill by Greg Whitworth (under development).