<!DOCTYPE html>
<html>
<body>
<textarea id="myTextarea" rows="4" cols="50">
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</textarea>
<p>Click the button to change the width of the text area.</p>
<button type="button" onclick="myFunction()">Try it</button>
<script>
function myFunction() {
document.getElementById("myTextarea").cols = "100";
}
</script>
</body>
</html>