JS的千分位演算法實作思路_javascript技巧

複製程式碼 程式碼如下:

function commafy() {
var getElementdocumf. "NumA").value;
//1.先去除空格,判斷是否空值與非數
num = num "";
num = num.replace(/[ ]/g, " ");
if (num == "") {
alert("空值，結束");
return;
}
if (isNaN(num)) {
alert("非數，結束");
return;
}
//2.針對是否有小數點，分情況處理
var index = num.indexOf(".");
if (index==-1) {//無小數點
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);
}