function limit(obj, limit) {
var val = obj.value;
if (len(val) > limit) {
val=val.substring(0,limit);
while (len(val) > limit){
val = val.substring(0, val.length - 1);
};
obj.value = val;
}
}
$("#nickName").keyup(function(){
limit(this,20);//Within 20 bytes
})
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
