复制代码 代码如下:

function commafy() {

var num = document.getElementById("NumA").value;

//1.先去除空格,判断是否空值和非数

num = num + "";

num = num.replace(/[ ]/g, "");

if (num == "") {

alert("空值，结束");

return;

}

if (isNaN(num)) {

alert("非数，结束");

return;

}

//2.针对是否有小数点，分情况处理

var index = num.indexOf(".");

if (index==-1) {//无小数点

var reg = /(-?d+)(d{3})/;

while (reg.test(num)) {

num = num.replace(reg, "$1,$2");

}

} else {

var intPart = num.substring(0, index);

var pointPart = num.substring(index + 1, num.length);

var reg = /(-?d+)(d{3})/;

while (reg.test(intPart)) {

intPart = intPart.replace(reg, "$1,$2");

}

num = intPart +"."+ pointPart;

}

return alert(num);

}