带小数点的

var a = 8462948.2453;console.log(a.toLocaleString()) //8,462,948.245

不带小数点的

num.toString().replace(/(\d)(?=(\d{3})+$)/g,'$1,')

满足两者情况的

function numFormat(num) {        var c = (num.toString().indexOf ('.') !== -1) ? num.toLocaleString() : num.toString().replace(/(\d)(?=(\d{3})+$)/g, '$1,');        return c;}