数字转千分位

将一串数字转为千分位格式：

  function numberChange_1(number){
       let num=number&&String(number)
       let floatNum=num.split(".")[1]; //浮点数
       let intNum=num.split(".")[0];  //整数
       let dianNum= intNum.split("").reverse();
       let qiequ="";
       dianNum.map((item,idex)=>{
           if((idex-2)%3==0){
              return qiequ+=`${item},`;
           }
           return  qiequ+=item;

       })
      let result= (qiequ.split("").reverse().join("")+"."+floatNum).replace(/^,/,"");
      return result;

   }

   function numberChange_2(number){
    return number && String(number) 
        .replace(/(\d)(?=(\d{3})+\.)/g, function(item, index){
            return item + ',';
        });
    }