javascript 如何在javascript中获得减去20秒的当前日期？
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how can I get the current date minus 20 seconds in javascript?
提问by user3147580
how can I get the current date minus 20 seconds in javascript? I can not figure out how to subtract 20 seconds to the current date in javascript how can I do, I get a negative value in this way
如何在javascript中获得减去20秒的当前日期？我不知道如何在 javascript 中将当前日期减去 20 秒我该怎么做，我以这种方式得到一个负值
There is an easier way? thanks
有更简单的方法吗？谢谢
var currentDate = new Date()
var day = currentDate.getDate()
var month = currentDate.getMonth() + 1
var year = currentDate.getFullYear()
var ora = currentDate.getHours()
var minuti = currentDate.getMinutes()
var secondi = currentDate.getSeconds()-20
回答by cookie monster
Give this a shot:
试一试：
new Date(Date.now() - 20000);
The Date.now()returns the milliseconds since Jan 1, 1970 00:00:00, so we just subtract 20000 milliseconds from that, and use the result to create a new date.
将Date.now()自1970年1月1日00:00:00返回毫秒，所以我们只是减去从20000毫秒，并使用结果来创建一个新的日期。
As @rjz noted, you'll need a shim for old IE. The MDN shim is below:
正如@rjz 所指出的，旧的 IE 需要一个垫片。MDN 垫片如下：
if (!Date.now) {
Date.now = function() { return new Date().getTime(); }
}
回答by Matt Johnson-Pint
回答by Michael Geary
I would do it something like this:
我会这样做：
function DateOffset( offset ) {
return new Date( +new Date + offset );
}
var twentySecondsAgo = DateOffset( -20000 );
// Should differ by 20 seconds (modulo 60)
alert(
twentySecondsAgo.getSeconds() +
'\n' +
new Date().getSeconds()
);
With this code you don't need any shims or polyfills or any of that stuff. I just tested it in IE 5.5 and Netscape 4.79 and it works fine there! That's why I used alert()in the test instead of console.log(), so I could test it in those old browsers.
使用此代码，您不需要任何垫片或 polyfill 或任何此类东西。我刚刚在 IE 5.5 和 Netscape 4.79 中测试了它，它在那里运行良好！这就是为什么我alert()在测试中使用而不是console.log()，所以我可以在那些旧浏览器中测试它。
回答by CRABOLO
Remove the - 20 that appears after getSeconds()
删除 getSeconds() 之后出现的 - 20
and then add this a line below it or more
然后在它下面添加一行或更多
secondi = secondi - 20;
