用于格式化时间的 Javascript 正则表达式

Question

Our organization's style guide specifies a date-time in this format: Dec. 31 08:45 am . Our site runs Drupal, which is a PHP-based CMS. Its field formatting templates allow for date-formatting strings specified in the encoding which is defined in HPHP's date() function. It only offers a , which gives pm , and A , which gives me PM , but I don't see anything specifying one with periods.

Unfortunately, there is not an easy way to hook in to the platform to define a custom date format, so I figure the simplest way forward is to do a find-and-replace with javascript. What I want to do is replace instances in the format NN:NN am and NN:NN pm with NN:NN am , etc.

Regexes have never been my strong suit. I can match date time format well enough( [0-9][0-9]:[0-9][0-9] pm ), but I don't know how to perform the proper replacement.

How can I replace am and pm with properly abbreviated version, when they follow a four-digit time format?

Answer 1

An alternative is using the optional handler in the function replace to get the match string and replace the am or pm strings with am or pm respectively.

 let str = "Dec. 31 08:45 am", result = str.replace(/([\\d][\\d]:[\\d][\\d] am|pm)/, function(match) { return match.replace('am', 'am').replace('pm', 'pm'); }); console.log(result);

Answer 2

str.replace(/(\d{2}:\d{2}\s?a|p)(m)/, '$1.$2');

Answer 3

You can use the following regex and replacement pattern to do, what you want:

Regex: ([0-2][0-9]:[0-5][0-9]\\s)(a|p)(m)

Replace: '$1$2.$3.'

How to use:

var text = 'Dec. 31 08:45 am';
text = text.replace(/([0-2][0-9]:[0-5][0-9] )(a|p)(m)/, '$1$2.$3.');

Answer 4

'Dec. 31 08:45 AM, Jan. 1 10:15 pm'.replace(/(\d{2}:\d{2}) (a|p)(m)/ig, (match, p1, p2, p3) => {
  return `${p1} ${p2}.${p3}.`.toLowerCase();
});

yields the result

Dec. 31 08:45 a.m., Jan. 1 10:15 p.m.