Only add thousand separator before decimal comma

Question

I have found a regex on stackoverflow to add a \',\' or \'.\' after every third number depending on your language.

(\\d)(?=(\\d\\d\\d)+(?!\\d))

Answer 1

You can try this:-

    function thousandsSeparator(input) {
    var output = input
    if (parseFloat(input)) {
        input = new String(input);
        var parts = input.split("."); 
        parts[0] = parts[0].split("").reverse().join("").replace(/(\d{3})(?!$)/g, "$1,").split("").reverse().join("");
        output = parts.join(".");
    }

    return output;
}

Answer 2

You can use your RegEx but split your number first if its has a comma or point in it.

jsFiddle demo

 var input = '5487445.46878';
 var parts = input.split('.');
 var part1 = parts[0].replace(/(\d)(?=(\d\d\d)+(?!\d))/g, "$1,");
 var part2 = parts[1];

 alert(part1 + '.' + part2);