Question

I want to format numbers. I have seen some of the regex expression example to insert comma in number string. All of them check 3 digits in a row and then insert comma in number. But i want something like this:

122 as 122
1234 as 1,234
12345 as 12,345
1723456 as 17,23,456
7123456789.56742 as 7,12,34,56,789.56742

I am very new to regex expression. Please help me how to display the number as the above. I have tried the below method. This always checks for 3 digits and then add comma.

function numberWithCommas(x) {
    return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
}

But i want comma every 2 digits except for the last 3 digits before the decimals as shown above.

Answer 1

Here’s a function to convert a number to a european (1.000,00 – default) or USA (1,000.00) style:

function sep1000(somenum,usa){
  var dec = String(somenum).split(/[.,]/)
     ,sep = usa ? ',' : '.'
     ,decsep = usa ? '.' : ',';
  return dec[0]
         .split('')
         .reverse()
         .reduce(function(prev,now,i){
                   return i%3 === 0 ? prev+sep+now : prev+now;}
                )
         .split('')
         .reverse()
         .join('') +
         (dec[1] ? decsep+dec[1] :'')
  ;
}

Alternative:

function sep1000(somenum,usa){
  var dec = String(somenum).split(/[.,]/)
     ,sep = usa ? ',' : '.'
     ,decsep = usa ? '.' : ',';

  return xsep(dec[0],sep) + (dec[1] ? decsep+dec[1] :'');

  function xsep(num,sep) {
    var n = String(num).split('')
       ,i = -3;
    while (n.length + i > 0) {
        n.splice(i, 0, sep);
        i -= 4;
    }
    return n.join('');
  }
}
//usage for both functions
alert(sep1000(10002343123.034));      //=> 10.002.343.123,034
alert(sep1000(10002343123.034,true)); //=> 10,002,343,123.034

[edit based on comment] If you want to separate by 100, simply change i -= 4; to i -= 3;

function sep100(somenum,usa){
  var dec = String(somenum).split(/[.,]/)
     ,sep = usa ? ',' : '.'
     ,decsep = usa ? '.' : ',';

  return xsep(dec[0],sep) + (dec[1] ? decsep+dec[1] :'');

  function xsep(num,sep) {
    var n = String(num).split('')
       ,i = -3;
    while (n.length + i > 0) {
        n.splice(i, 0, sep);
        i -= 3;  //<== here
    }
    return n.join('');
  }
}