How to validate date format using jquery

In front-end development, we often encounter situations where we need to verify the date format. jquery is a very convenient and easy-to-use tool library. It can help us easily complete the verification of the date format. This article will introduce how to use jquery to verify the date. Format.

1. Introduction of jquery library
Before using jquery to verify the date format, we need to introduce the jquery library first. You can introduce the local jquery library or introduce it through CDN:

<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>

2 , Use regular expressions to verify the date format
You can use regular expressions to verify the date format. jquery provides a regular expression verification method $.trim(), which can remove spaces in the string and Invalid characters such as newline characters. You can use the following regular expressions:

var reg = /^(\d{4})-(\d{2})-(\d{2})$/;

The above regular expressions can verify the date format in the form of "2021-05-01", where \d represents a number, {n } means n consecutive occurrences, ^ means matching the beginning of the string, $ means matching the end of the string, () means grouping.
We can use the following code to verify the date format using regular expressions:

var date = $('#date').val();
if ($.trim(date).match(reg) == null) {
    alert("日期格式不正确，请重新输入");
}

In the above code, #date represents the date input box to be verified, val() The method can get the value in the input box, the $.trim() method removes invalid characters such as spaces and newlines, and the match() method is used to match strings with regular The expression is matched, and if the return value is null, it means that the date format is incorrect.

3. Use the moment.js plug-in to verify the date format
In addition to regular expression verification of the date format, you can also use the moment.js plug-in to verify the date format. It is a very powerful date processing tool. , which can handle various date formats conveniently.
Use moment.js to verify the date format code as follows:

var date = $('#date').val();
if (!moment(date).isValid()) {
    alert("日期格式不正确，请重新输入");
}

In the above code, the moment() method converts the input date string into a moment object, and the isValid() method is used to check whether the date is valid. If the date is illegal, return false.

4. Conclusion
This article introduces two methods of how jquery verifies the date format: using regular expressions and using the moment.js plug-in. No matter which method is used, you need to introduce the jquery library or moment.js plug-in first. The regular expression verification method is simpler, but has certain limitations. It is only suitable for dates in a specific format, while the moment.js plug-in can handle more There are many date formats, but a lot of code is introduced, which also has a certain impact on page performance. Which method to use can be chosen according to the actual situation.

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