Javascript IsInteger

A simple and javascript function to check whether the string is an integer.

function isInteger(s){
var i;
    for (i = 0; i < s.length; i++){
        // Check that current character is number.
        var c = s.charAt(i);
        if (((c < "0") || (c > "9"))){
return false;
}
    }
    // All characters are numbers.
    return true;
}