如何在 javascript 中比较两个字符串日期？

我有两个 m/d/yyyy 格式的字符串日期。例如，“11/1/2012”，“1/2/2013”。我正在用 JavaScript 编写一个函数来比较两个字符串日期。我函数的签名是 如果 string1传递的日期晚于 string2传递的日期，它将返回 true，否则返回 false。 因此，isLater (“1/2/2013”，“11/1/2012”)应该返回 true？

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Parse the dates and compare them as you would numbers:

function isLater(str1, str2)
{
return new Date(str1) > new Date(str2);
}

If you need to support other date format consider a library such as date.js.

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最佳答案 
var d1 = Date.parse("2012-11-01");
var d2 = Date.parse("2012-11-04");
if (d1 < d2) {
alert ("Error!");
}

Demo Jsfiddle

Recently found out from a comment you can directly compare strings like below

if ("2012-11-01" < "2012-11-04") {
alert ("Error!");
}
小开

You can simply compare 2 strings

function isLater(dateString1, dateString2) {
return dateString1 > dateString2
}

Then

isLater("2012-12-01", "2012-11-01")

returns true while

isLater("2012-12-01", "2013-11-01")

returns false

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If your date is not in format standar yyyy-mm-dd (2017-02-06) for example 20/06/2016. You can use this code

var parts ='01/07/2016'.val().split('/');
var d1 = Number(parts[2] + parts[1] + parts[0]);
parts ='20/06/2016'.val().split('/');
var d2 = Number(parts[2] + parts[1] + parts[0]);
return d1 > d2
小开

Directly parsing a date string that is not in yyyy-mm-dd format, like in the accepted answer does not work. The answer by vitran does work but has some JQuery mixed in so I reworked it a bit.

// Takes two strings as input, format is dd/mm/yyyy
// returns true if d1 is smaller than or equal to d2


function compareDates(d1, d2){
var parts =d1.split('/');
var d1 = Number(parts[2] + parts[1] + parts[0]);
parts = d2.split('/');
var d2 = Number(parts[2] + parts[1] + parts[0]);
return d1 <= d2;
}

P.S. would have commented directly to vitran's post but I don't have the rep to do that.

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You can use "Date.parse()" to properly compare the dates, but since in most of the comments people are trying to split the string and then trying to add up the digits and compare with obviously wrong logic -not completely.

Here's the trick. If you are breaking the string then compare the parts in nested format.

Compare year with year, month with month and day with day.

<pre><code>


var parts1 = "26/07/2020".split('/');
var parts2 = "26/07/2020".split('/');


var latest = false;


if (parseInt(parts1[2]) > parseInt(parts2[2])) {
latest = true;
} else if (parseInt(parts1[2]) == parseInt(parts2[2])) {
if (parseInt(parts1[1]) > parseInt(parts2[1])) {
latest = true;
} else if (parseInt(parts1[1]) == parseInt(parts2[1])) {
if (parseInt(parts1[0]) >= parseInt(parts2[0])) {
latest = true;
}
}
}


return latest;


</code></pre>
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This worked for me in nextjs/react

import { format, parse, isBefore } from "date-fns";

...

{isBefore(new Date(currentDate), new Date(date)) ? (
<span>Upcoming Event</span>
) : (
<span>Past Event</span>
)}

...

isBefore(date, dateToCompare)

https://date-fns.org/docs/isBefore


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