Cách 1: 
Number(10000).toLocaleString('en');  // "10,000"
cách 2: 
function commaSeparateNumber(val){
    while (/(\d+)(\d{3})/.test(val.toString())){
      val = val.toString().replace(/(\d+)(\d{3})/, '$1'+','+'$2');
    }
    return val;
  }
$('#elementID').html(commaSeparateNumber(1234567890));