How to validate input using JavaScript?

I am to check the number of occurrenc开发者_如何转开发es of a numeric value in a string i.e in that string only 2 numeric characters are allowed. Can anyone help me to solve this?

Thanks in advance

Try this code

    var s ="1asds3asa"; // string to check
    var t = s.replace(/[^\d]/g,""); // a string with everything but the digits removed
    if(t.length>2)
    {
       alert("Only 2 numbers allowed");
    }