js numerical value converted to 3-digit comma separated sample code_javascript skills

Example code:

Copy code The code is as follows:

function formatNum(strNum) {

if (strNum.length <= 3) {

return strNum;

}

if (!/^( |-)?(d )(.d )?$/.test(strNum)) {

return strNum;

}

var a = RegExp.$1, b = RegExp.$2, c = RegExp.$3;

var re = new RegExp();

re.compile("(\d)(\d{3})(,|$)");

while (re.test(b)) {

b = b.replace(re, "$1,$2$3");

}

return a "" b "" c;

}