How to do Javascript calculations by accepting a comma to separate decimal places

You can use replace where you delimit the character to be replaced and then pass it to float :

var comVigula = "1,87";
comVirgula = parseFloat(comVirgula.replace(',','.'));
alert(comVirgula);

After this just use as you want in your code.

Use the following Javascript methods

• replace to change the comma per point
• parseFloat to convert to float / double
• toFixed to set how many decimal places you want after the comma

var string1 = '21,21';
var string2 = '10,8';

var numero1 = parseFloat(string1.replace(',', '.'));
var numero2 = parseFloat(string2.replace(',', '.'));

document.write('Número 1: <b>' + numero1 + '</b><br />');
document.write('Número 2: <b>' + numero2 + '</b><br />');
document.write('Soma: <b>' + (numero1 + numero2).toFixed(2) + '</b><br />');

Let's assume that the value formatted in money is: $ 1,234.53

In the example above you will have a semicolon, in this case, if you use .replace(',','.') , your output number would look like this: 1,234 , but the correct one should be 1234.53 . Think now of thousands ( 1,000,000,000.00 ), how many formatting would you need, then it would be ideal if you had a general rule for everyone, avoiding future upheavals, you can create a following way, regardless of the input value:

//em float
formatNumber(1234.53);
//em string real
formatNumber('1.234,53');
//em string real sem ponto
formatNumber('1234,53');
//em string americano
formatNumber('1,234.53');

//retornará 1234.53
function formatNumber(value) {
    value = convertToFloatNumber(value);
    return value.formatMoney(2, '.', '');
}
//retornará 1.234,53
function formatNumber(value) {
    value = convertToFloatNumber(value);
    return value.formatMoney(2, ',', '.');
}
//retornará 1,234.53
function formatNumber(value) {
    value = convertToFloatNumber(value);
    return value.formatMoney(2, '.', ',');
}

 //transforma a entrada em número float
 var convertToFloatNumber = function(value) {
     value = value.toString();
      if (value.indexOf('.') !== -1 && value.indexOf(',') !== -1) {
          if (value.indexOf('.') <  value.indexOf(',')) {
             //inglês
             return parseFloat(value.replace(/,/gi,''));
          } else {
            //português
             return parseFloat(value.replace(/./gi,'').replace(/,/gi,'.'));
          }      
      } else {
         return parseFloat(value);
      }
   }

//prototype para formatar a saída  
Number.prototype.formatMoney = function (c, d, t) {
    var n = this,
        c = isNaN(c = Math.abs(c)) ? 2 : c,
        d = d == undefined ? "." : d,
        t = t == undefined ? "," : t,
        s = n < 0 ? "-" : "",
        i = parseInt(n = Math.abs(+n || 0).toFixed(c)) + "",
        j = (j = i.length) > 3 ? j % 3 : 0;
    return s + (j ? i.substr(0, j) + t : "") + i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + t) + (c ? d + Math.abs(n - i).toFixed(c).slice(2) : "");
};