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@arodu
Created February 4, 2019 13:09
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textarea autoresize vanillajs
<!DOCTYPE html>
<html lang="en" dir="ltr">
<head>
<meta charset="utf-8">
<title>textarea autoresize</title>
<style media="screen">
textarea {
min-height: 5em;
width: 100%;
resize:none;
}
</style>
</head>
<body>
<textarea></textarea>
<script type="text/javascript">
var autoExpand = function (field) {
// Reset field height
field.style.height = 'inherit';
// Get the computed styles for the element
var computed = window.getComputedStyle(field);
// Calculate the height
var height = parseInt(computed.getPropertyValue('border-top-width'), 10)
+ parseInt(computed.getPropertyValue('padding-top'), 10)
+ field.scrollHeight
+ parseInt(computed.getPropertyValue('padding-bottom'), 10)
+ parseInt(computed.getPropertyValue('border-bottom-width'), 10);
field.style.height = height + 'px';
};
document.addEventListener('input', function (event) {
if (event.target.tagName.toLowerCase() !== 'textarea') return;
autoExpand(event.target);
}, false);
</script>
</body>
</html>
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