I have function in JavaScript:

function calc(num) {
    if (num <= 22) {
            return parseInt(num);
    } else {
            num += '';
            var curr = 0;
            for (var i = 0; i < num['length']; i++) {
                    curr += parseInt(num[i]);
            };
            return curr;
    };
};

This function calculates new number like: if I have number greater than 22, this function returns new number which is a sum of it's subdigits (e.g. 28 > 22 => return (2+8) ).

This function works great in Firefox, but I'm getting "NaN" error in Internet Explorer with numbers greater than 22. So the problem must be in "else".

What's wrong?

I have function in JavaScript:

function calc(num) {
    if (num <= 22) {
            return parseInt(num);
    } else {
            num += '';
            var curr = 0;
            for (var i = 0; i < num['length']; i++) {
                    curr += parseInt(num[i]);
            };
            return curr;
    };
};

This function calculates new number like: if I have number greater than 22, this function returns new number which is a sum of it's subdigits (e.g. 28 > 22 => return (2+8) ).

This function works great in Firefox, but I'm getting "NaN" error in Internet Explorer with numbers greater than 22. So the problem must be in "else".

What's wrong?

• javascript
• internet-explorer
• parseint

• 2 Please supply a decimal radix to parseInt(): parseInt(num[i], 10). It's a very bad habit to omit that second parameter. – Michael Berkowski Commented Oct 25, 2011 at 16:57
• 1 A guess: Try num = num + ''; if += is not defined for string concatenation. – Hogan Commented Oct 25, 2011 at 16:57
• I've tried radix, but no effect – xZ6a33YaYEfmv Commented Oct 25, 2011 at 16:58
• 2 Try num.charAt(i) instead of num[i]. I think IE does not implement array access for strings. – Felix Kling Commented Oct 25, 2011 at 17:00
• 3 @ieaglle - even if radix isn't the solution to this problem, you should still include it; as Michael says, it is bad practice to omit it, and it will e back to bite you one day. – Spudley Commented Oct 25, 2011 at 17:02

2 Answers 2

You need to num.charAt(i) as you cannot access string characters with String[offset] in IE.

(s = "qwe"; alert(typeof s[1] === 'undefined') is true)

Try this:

function calc(num) {
    if (num <= 22) {
            return parseInt(num);
    } else {
            number = num.toString();
            var curr = 0;
            for (var i = 0; i < number.length; i++) {

                    curr += parseInt(number.charAt(i));
            };
            return curr;
    };
};


alert(calc(23));

worked for me on firefox and IE