数字&金额格式化

var formatNumber = numStr => {
    numStr += '';
    x = numStr.split('.');
    x1 = x[0];
    x2 = x.length > 1 ? '.' + x[1] : '';
    var rgx = /(\d+)(\d{3})/;
    while (rgx.test(x1)) {
      x1 = x1.replace(rgx, '$1' + ',' + '$2');
    }
    return x1 + x2;
  }

formatNumber(10000000000);  // "10,000,000,000"