Price calculation, comma, and conditional statement

All sorts of topics are dedicated to the European comma problem, i.e. How to change the ',' to an '.', But I've not found a solution for mine yet.

I want users to be able to input in the comma-value manner (e.g. 3,99), Then calculate some stuff and output some of it again in comma's. The if-statement should mention that if the price at the end (earnings) turns negative, it turns red (i.e. NOT possible).

I am able to change the point to a comma and output that, but the other way around I'm dazzled. Here's my code thus far:

I've managed to get the whole thing working based on @Zirak's comments and a little bit of me-magic, see code below!

function dollarformat(num) {
    num = num.toString().replace(/\u20ac/g, 'Euro');
    if(isNaN(num)) num = "0";
        cents = Math.floor((num*100+0.5)%100);
        num = Math.floor((num*100+0.5)/100).toString();
    if(cents < 10) cents = "0" + cents;
        for (var i = 0; i < Math.floor((num.length-(1+i))/3); i++)
            num = num.substring(0,num.length-(4*i+3))+','+num.substring(num.length-(4*i+3));
    return (num + ',' + cents);}

$('#prijsnow').keyup(function(num) {

        var comma = $(this).val().replace(',', '.');
        $('#vat').text(dollarformat(comma / 119 * 100));
        $('#earnings').text(dollarformat(comma / 119 * 25));
                // 0.80 is the minimum amount, I've put it in hardcode (could be dynamic as well)
        if (comma < 0.80) { $('#earnings').text(0); } else {$('#earnings').text(dollarformat(comma / 119 *开发者_如何学JAVA 75 - 0.50))};

                // Nice fix for the colour problem, easy CSS attribution
        if (comma < 0.80) { $('#earnings').css("color","red"); } 
        if (comma > 0.80) { $('#earnings').css("color","green"); }

    });

Just looking at the script you shouldn't have a problem.

if (/\./.test(num))
    num.replace('.', ',');
//Or if you want the other way around
if (/\,/.test(num))
    num.replace(',', '.');

For the negative price, you can use a class:

if( $(earnings).val() < 0 )
    $(earnings).addClass('negativeVal');

And in your CSS:

.negativeVal {
    color : red;
}

Also, to save you trouble: Did you try splitting the number using split?

As described above, a possible way to fix this problem is:

function dollarformat(num) {
    num = num.toString().replace(/\u20ac/g, 'Euro');
    if(isNaN(num)) num = "0";
        cents = Math.floor((num*100+0.5)%100);
        num = Math.floor((num*100+0.5)/100).toString();
    if(cents < 10) cents = "0" + cents;
        for (var i = 0; i < Math.floor((num.length-(1+i))/3); i++)
            num = num.substring(0,num.length-(4*i+3))+','+num.substring(num.length-(4*i+3));
    return (num + ',' + cents);}

$('#prijsnow').keyup(function(num) {

        var comma = $(this).val().replace(',', '.');
        $('#vat').text(dollarformat(comma / 119 * 100));
        $('#earnings').text(dollarformat(comma / 119 * 25));
                // 0.80 is the minimum amount, I've put it in hardcode (could be dynamic as well)
        if (comma < 0.80) { $('#earnings').text(0); } else {$('#earnings').text(dollarformat(comma / 119 * 75 - 0.50))};

                // Nice fix for the colour problem, easy CSS attribution
        if (comma < 0.80) { $('#earnings').css("color","red"); } 
        if (comma > 0.80) { $('#earnings').css("color","green"); }

    });