How to autogrow a textarea with CSS?

Question

Given a textarea that starts off as a small box, single line, is it possible using CSS to automatically grow to have multiple lines as the user types multiple lines up until say a set limit (300px) when a scrollbar would appear with overflow auto with all the inputs?

Answer 1

2020 Update - Using contenteditable

Because this answer still helps some folks from time to time, I felt like updating my answer with Chris Coiyer's latest finding.

Be warned, it is still not a CSS3 solution. But it's built-in the browser and recreates the OP's sought behavior.

Using contenteditable HTML attribute on a <div /> will allow the user to edit the text content of a div and expand as the user breaks the line. Then, just deguise your div into a <textarea />.

<div    class="expandable-textarea"   role="textbox"   contenteditable >     Your default value </div> 

.expandable-textarea {   border: 1px solid #ccc;   font-family: inherit;   font-size: inherit;   padding: 1px 6px;    display: block;   width: 100%;   overflow: hidden;   resize: both;   min-height: 40px;   line-height: 20px; } 

The one caveat to this solution, is we're not using textareas. Bear in mind some of the features, such as placeholder, will require some creativity to be implemented using a <div contenteditable />

Source: The Great Chris Coiyer. Link to his blog

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Original Answer: Workaround using a light-weight JS lib

Unfortunately, it seems that you cannot do this with only CSS3.

But, there's a 3.2k minified JS alternative to do so.

Here's the link including demo and usage.

You can install it by doing npm install autosize and using this way

autosize(document.querySelector('.yourTextAreaClass')); 

Or jQuery style

autosize($('.yourTextAreaClass')); 

And it works like a charm. It's lightweight and has a natural feel unlike many autoresize that are doing useless animations.

Answer 2

Chris Coyier (of CodePen fame) just posted a grid-based CSS-only implementation of this. From Original CodePen by Chris Coyier - October 30th, 2020

.grow-wrap {   /* easy way to plop the elements on top of each other and have them both sized based on the tallest one's height */   display: grid; }  .grow-wrap::after {   /* Note the weird space! Needed to preventy jumpy behavior */   content: attr(data-replicated-value) " ";   /* This is how textarea text behaves */   white-space: pre-wrap;   /* Hidden from view, clicks, and screen readers */   visibility: hidden; }  .grow-wrap>textarea {   /* You could leave this, but after a user resizes, then it ruins the auto sizing */   resize: none;   /* Firefox shows scrollbar on growth, you can hide like this. */   overflow: hidden; }  .grow-wrap>textarea, .grow-wrap::after {   /* Identical styling required!! */   border: 1px solid black;   padding: 0.5rem;   font: inherit;   /* Place on top of each other */   grid-area: 1 / 1 / 2 / 2; }  body {   margin: 2rem;   font: 1rem/1.4 system-ui, sans-serif; }  label {   display: block; }

<form action="#0">   <label for="text">Text:</label>   <div class="grow-wrap">     <textarea name="text" id="text" onInput="this.parentNode.dataset.replicatedValue = this.value"></textarea>   </div> </form>

License:

Copyright (c) 2020 by Chris Coyier (https://codepen.io/chriscoyier/pen/XWKEVLy)

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