用javascript限制字数显示个数

<textarea name="个人介绍" cols="50" rows="6" class="bot" id="youbian" onkeyup="checkLength(this)"></textarea>
限制字符，显示剩余字符数，最大长度: 300
还剩: <span id="chLeft">300</span>

<script type="text/javascript">
function checkLength(which) {
var maxChars = 300;
if (which.value.length > maxChars)
which.value = which.value.substring(0,maxChars);
var curr = maxChars - which.value.length;
document.getElementById("chLeft").innerHTML = curr.toString();
}
</script>
下面的是限制字数（不含空格），最大字数为200字
function checkLength(which) {
var maxChars = 200;
var noSpace_val=which.value.replace(/(s*)/g,"");
var curr = maxChars - noSpace_val.length;
if(curr.toString() < 0){
var length=which.value.length;
which.value = which.value.substring(0,length+curr);
}else{
document.getElementById("chLeft").innerHTML = curr.toString();
}
}