function number_format(a, b, c, d) {
 // number_format(number, decimals, comma, formatSeparator)
 a += '';
 var k = '';
 if(a.indexOf('-') == 0) {
  k = '-';
  a = a * -1;
 }
 a = Math.round(a * Math.pow(10, b)) / Math.pow(10, b);
 var e = a + '';
 var f = e.split('.');
 if(!f[0]) f[0] = '0';
 if(!f[1]) f[1] = '';
 if(f[1].length < b){
  var g = f[1];
  for(var i = f[1].length + 1; i <= b; i++) {
   g += '0';
  }
  f[1] = g;
 }
 if(d != '' && f[0].length > 3) {
  var h = f[0];
  f[0] = '';
  for(var j = 3; j < h.length; j += 3) {
   i = h.slice(h.length - j, h.length - j + 3);
   f[0] = d + i +  f[0] + '';
  }
  j = h.substr(0, (h.length % 3 == 0) ? 3 : (h.length % 3));
  f[0] = j + f[0];
 }
 c = (b <= 0) ? '': c;
 return k + f[0] + c + f[1];
}