Question

I found that when jQuery get a value with 0 (for example 100)trail, it will omit it. So if I compare 5>100, the result is true. So how do I solve this?
here is the HTML code:

<form id="target">
    <input type="text" id="max"  value="100"/>
    <input type="text" id="number" />
    <input id="submit" type="submit" value="submit" />
</form>

And here is jquery:

$('#target').submit( function() {
  var a = $("#number").val();
  var b = $("#max").val();
  if( a > b){
     alert("exceed limit"); 
  }

return false;
});

Here you can see demo: http://jsfiddle.net/yqMGG/91/

Answer 1

You need to compare the numeric values, not the string values. The output of the .val() function is a DOMString value according to DOM Level 2 which says:

interface HTMLInputElement : HTMLElement {
  ...
  attribute DOMString       value;
  ...
}

so your (5 > 100) test is really "5" > "100" which is true since strings are compared lexicographically.

The solution is to change

if( a > b){

to

if(+a > +b){

The + prefix operator coerces its argument to a number.