数字每三位加逗号,小数保留4位

function numTransfrom(num){
let int,float,strArr,str="";
function numb(int, str, len){
let i = len - 3;
if (i > 0) {
str = "," + int.substr(i, 3).concat(str);
return numb(int, str, i);
} else {
return str = int.substr(0, len).concat(str);
}
}
strArr = num.toString().split(".");
[int, float = "0"] = [...num.toString().split(".")];
str = numb(int,str,int.length);
if(float.length > 4){
str += "." + float.substr(0,4);
}else{
str += "." + float.padEnd(4,"0");
}
console.log(str);
}

numTransfrom(3123132423434.23232432)

数字每三位加逗号,小数保留4位

原文：https://www.cnblogs.com/zouyun/p/9698840.html