simple-element-resize-detector

by luwes

HTML

<script src="https://unpkg.com/simple-element-resize-detector"></script>
<span id="log">resize the textarea</span>

<div id="foo">
	<textarea resize></textarea>
</div>

CSS

#foo {
	position: relative;
	display: inline-block;
	overflow: hidden;
}

JavaScript

var el = document.getElementById('foo');
var log = document.getElementById('log');

function onResize() {
	log.textContent = (
		el.offsetWidth + ' x ' + el.offsetHeight
	);
}

simpleElementResizeDetector(el, onResize);