为什么这个 Javascript 脚本没有给出 ant 输出？

Question

我想制作一个简单的实时日期计数器，它会在脚本位于文件中的任何位置输出到 html 中。这是 JSFiddle，这是脚本：

var today = newDate();
var dd = today.getDate();
var mm = today.getMonth();
var yyyy = today.getFullYear();

if (dd = 1 || 21 || 31) {
    dd = dd + 'st'
} else if (dd = 2 || 22) {
    dd = dd + 'nd'
} else if (dd = 3 || 23) {
    dd = dd + 'nd'
} else {
    dd = dd + 'th'
}

if (mm = 0) {
    mm = "JANUARY";
} else if (mm = 1) {
    mm = "FEBRUARY";
} else if (mm = 2) {
    mm = "MARCH";
} else if (mm = 3) {
    mm = "APRIL";
} else if (mm = 4) {
    mm = "MAY";
} else if (mm = 5) {
    mm = "JUNE";
} else if (mm = 6) {
    mm = "JULY";
} else if (mm = 7) {
    mm = "AUGUST";
} else if (mm = 8) {
    mm = "SEPTEMBER";
} else if (mm = 9) {
    mm = "OCTOBER";
} else if (mm = 10) {
    mm = "NOVEMBER";
} else {
    mm = "DECEMBER";
}

today = dd + '|' + mm + '|' + yyyy;
document.write(today);

我知道这是编写任何一般代码的最低效且可能不正确的方式（这是我在 JS 中做过的第二件事。）但请接受我的愚蠢错误。

非常感谢。

Answer 1

使用

var today = new Date();

改为

var today = newDate();

输出将是“1st|FEBRUARY|2015”

---

更新：（更优雅的方式）

b=(new Date()).toLocaleString('en-us', {
  day: 'numeric',
  month: "long",
  year: 'numeric'
}).replace(/(\w+) (\d+), (\d+)/, '$2|$1|$3'); // 30|June|2015
dd=parseInt(b, 10);
op='';
suffix =["st","nd","rd","th"];
if(parseInt(dd) > 4)
    op=dd+""+suffix[3];
else
    op=dd+""+suffix[(parseInt(dd)%10)-1];
alert(b.replace(/^\d+/, op))

Answer 2

避免 if 的级联

var month = ["January", "Feb", "March",....,"Dec"];//store array of months as string
var suffix =["st","nd","rd","th"];
var today = new Date();
var dd = today.getDate();
var mm = today.getMonth();
var yyyy = today.getFullYear();
var op="";
if(parseInt(dd) > 4)
    op+=dd+""+suffix[3]+"|";
else
    op+=dd+""+suffix[(parseInt(dd)%10)-1]+"|";
op+=month[parseInt(mm)]+"|"+yyyy;

让它变得简单 working fiddle

仅供参考：刚刚看到 answer 和 0-11 几个月，而 0 代表一月，11 代表十二月

Answer 3

不要重新发明轮子，只需使用moment.js：

var d = new Date();

document.write(moment().format('Do|MMMM|YYYY'));

<script src="https://raw.githubusercontent.com/moment/moment/develop/moment.js"></script>

Answer 4

只要写：var today = new Date();