Limit input text, the easy way

HTML
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<form>
<textarea cols=100 rows=20 onkeyup="change(this);"></textarea>
<br>You've typed <span id="char_cnt">0</span> character(s). You
are allowed <span id="chars_left">lots</span> more.
</form>
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JAVASCRIPT
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<script type="text/javascript">
function change (el) {
var max_len = 10;
if (el.value.length > max_len) {
el.value = el.value.substr(0, max_len);
}
document.getElementById('char_cnt').innerHTML = el.value.length;
document.getElementById('chars_left').innerHTML = max_len - el.value.length;
return true;
}
</script>
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