格式化金额到千分位

方法一：

// 格式化金额(无保留小数)
function toThousands(num) {
  var result = [], counter = 0;
  num = (num || 0).toString().split('');
  for (var i = num.length - 1; i >= 0; i--) {
    counter++;
    result.unshift(num[i]);
    if (!(counter % 3) && i != 0) { result.unshift(','); }
  }
  return result.join('');
}

方法二：

/**
 * 将数值四舍五入(保留2位小数)后格式化成金额形式
 * @param num 数值(Number或者String)
 * @return 金额格式的字符串,如'1,234,567.45'
 * @type String
 */
function formatCurrency(num) {
  num = num.toString().replace(/\$|\,/g, '');
  if (isNaN(num))
    num = "0";
  let sign = (num == (num = Math.abs(num)));
  num = Math.floor(num * 100 + 0.50000000001);
  let cents = num % 100;
  num = Math.floor(num / 100).toString();
  if (cents < 10)
    cents = "0" + cents;
  for (var i = 0; i < Math.floor((num.length - (1 + i)) / 3); i++)
    num = num.substring(0, num.length - (4 * i + 3)) + ',' + num.substring(num.length - (4 * i + 3));
  return (((sign) ? '' : '-') + num + '.' + cents);
}

方法三：

function formatPrice(num) {
  let flag = false
  if (num) {
    if (num < 0) {
      num = Math.abs(num)
      flag = true
    } 
    var numArr = num.toFixed(2).split(".")
    var termArr = []
    var lastArr = []
    for (let i = numArr[0].length; i > 0; i -= 3) {
      termArr.unshift(numArr[0].substring(i - 3, i))
    }
    lastArr.push(termArr.join(","))
    lastArr.push(numArr[1])
  } else {
    lastArr = ["0"]
  }
  return flag ? ('-' + lastArr.join(".")) : lastArr.join(".")
}

方法四：简单粗暴

function toThousands(num) {
  return num.toLocaleString()
}