JS正则表达式兑现千分位

JS正则表达式实现千分位function format(val){return (val+).replace(/(\d)(?(\d{3})+$)/g, $1,)}

JS正则表达式实现千分位

function format(val){  return (val+"").replace(/(\d)(?=(\d{3})+$)/g, "$1,");}