Question

I have written a bunch of code to have a valid entry for Spend amount (32.4554, 234,324.34, etc.). I have additionally written code to limit the user from entering more than 13 digits (excluding . and ,).

All of this works perfectly in Firefox. But in IE 8, after the number of digits exceeds 13, if a letter is entered, Internet Explorer hangs and crashes! While debugging I noticed it faulting at the regex line, but the same regex works fine until that limit of 13 isn’t crossed! Regexperts, please! Show me the light!

function isIncorrectSpend(cubeCurrencySpend) {  
    if(!(/^([1-9]*[0-9]*,?[0-9]*)* (\.[0-9]*)?$/.test(cubeCurrencySpend))) {
        return true;
    }
    return false;
}

function isLongerThanThirteenDigits(cubeCurrencySpend) {
    cubeCurrencySpend = cubeCurrencySpend.replace(/,/g, "").replace(/\./g, "");
    if(cubeCurrencySpend.length>12) { 
        return true;
    }
    return false;
}

jQuery("input#minval").keyup( function() {
    if(isIncorrectSpend(jQuery("input#minval").val())) {
        jQuery("input#minval").val("");
        alert("please enter correct spend value");
    }        
});
jQuery("input#minval").keypress( function(e) {
    var code = (e.keyCode ? e.keyCode : e.which);
    if(isLongerThanThirteenDigits(jQuery("input#minval").val()) && (code > 47 && code < 58)) {
        alert("Please enter a number less than 13 digits");
        return false;
    }
    return true;
});

Answer 1

I am quite sure this is a case of catastrophic backtracking. Your regex has too many possibilities to check, till it can fail.

The problem is this part

([1-9]*[0-9]*,?[0-9]*)*

and I am quite sure it is not doing what you expect it to.

This will match the same stuff, but will fail much quicker:

/^[1-9]*[0-9,]*(\.[0-9]+)?$/

it is still allowing stuff like 1,,,,,,,.123, but much better than yours. If you want to disallow such things, you need to clarify your requirements.