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How to parse a time into a Date object from user input in JavaScript?

Asked 2008-09-26T19:13:02.237
82

I am working on a form widget for users to enter a time of day into a text input (for a calendar application). Using JavaScript (we are using jQuery FWIW), I want to find the best way to parse the text that the user enters into a JavaScript Date() object so I can easily perform comparisons and other things on it.

I tried the parse() method and it is a little too picky for my needs. I would expect it to be able to successfully parse the following example input times (in addition to other logically similar time formats) as the same Date() object:

  • 1:00 pm
  • 1:00 p.m.
  • 1:00 p
  • 1:00pm
  • 1:00p.m.
  • 1:00p
  • 1 pm
  • 1 p.m.
  • 1 p
  • 1pm
  • 1p.m.
  • 1p
  • 13:00
  • 13

I am thinking that I might use regular expressions to split up the input and extract the information I want to use to create my Date() object. What is the best way to do this?

javascript datetime parsing date time
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3 Answers

80

A quick solution which works on the input that you've specified:

function parseTime( t ) {
   var d = new Date();
   var time = t.match( /(\d+)(?::(\d\d))?\s*(p?)/ );
   d.setHours( parseInt( time[1]) + (time[3] ? 12 : 0) );
   d.setMinutes( parseInt( time[2]) || 0 );
   return d;
}

var tests = [
  '1:00 pm','1:00 p.m.','1:00 p','1:00pm','1:00p.m.','1:00p','1 pm',
  '1 p.m.','1 p','1pm','1p.m.', '1p', '13:00','13', '1a', '12', '12a', '12p', '12am', '12pm', '2400am', '2400pm', '2400', 
  '1000', '100', '123', '2459', '2359', '2359am', '1100', '123p',
  '1234', '1', '9', '99', '999', '9999', '99999', '0000', '0011', '-1', 'mioaw' ];

for ( var i = 0; i < tests.length; i++ ) {
  console.log( tests[i].padStart( 9, ' ' ) + " = " + parseTime(tests[i]) );
}

It should work for a few other varieties as well (even if a.m. is used, it'll still work - for example). Obviously this is pretty crude but it's also pretty lightweight (much cheaper to use that than a full library, for example).

Warning: The code doe not work with 12:00 AM, etc.

answered 2008-09-26T19:44:31.240
3

I came across a couple of kinks in implementing John Resig's solution. Here is the modified function that I have been using based on his answer:

function parseTime(timeString)
{
  if (timeString == '') return null;
  var d = new Date();
  var time = timeString.match(/(\d+)(:(\d\d))?\s*(p?)/);
  d.setHours( parseInt(time[1]) + ( ( parseInt(time[1]) < 12 && time[4] ) ? 12 : 0) );
  d.setMinutes( parseInt(time[3]) || 0 );
  d.setSeconds(0, 0);
  return d;
} // parseTime()

var tests = [
  '1:00 pm','1:00 p.m.','1:00 p','1:00pm','1:00p.m.','1:00p','1 pm',
  '1 p.m.','1 p','1pm','1p.m.', '1p', '13:00','13', '1a', '12', '12a', '12p', '12am', '12pm', '2400am', '2400pm', '2400', 
  '1000', '100', '123', '2459', '2359', '2359am', '1100', '123p',
  '1234', '1', '9', '99', '999', '9999', '99999', '0000', '0011', '-1', 'mioaw' ];

for ( var i = 0; i < tests.length; i++ ) {
  console.log( tests[i].padStart( 9, ' ' ) + " = " + parseTime(tests[i]) );
}

answered 2008-10-31T14:21:17.537
3

Here's a solution more for all of those who are using a 24h clock that supports:

  • 0820 -> 08:20
  • 32 -> 03:02
  • 124 -> 12:04

function parseTime(text) {
  var time = text.match(/(\d?\d):?(\d?\d?)/);
 var h = parseInt(time[1], 10);
 var m = parseInt(time[2], 10) || 0;
 
 if (h > 24) {
        // try a different format
  time = text.match(/(\d)(\d?\d?)/);
  h = parseInt(time[1], 10);
  m = parseInt(time[2], 10) || 0;
 } 
 
  var d = new Date();
  d.setHours(h);
  d.setMinutes(m);
  return d;  
}

var tests = [
  '1:00 pm','1:00 p.m.','1:00 p','1:00pm','1:00p.m.','1:00p','1 pm',
  '1 p.m.','1 p','1pm','1p.m.', '1p', '13:00','13', '1a', '12', '12a', '12p', '12am', '12pm', '2400am', '2400pm', '2400', 
  '1000', '100', '123', '2459', '2359', '2359am', '1100', '123p',
  '1234', '1', '9', '99', '999', '9999', '99999', '0000', '0011', '-1', 'mioaw' ];

for ( var i = 0; i < tests.length; i++ ) {
  console.log( tests[i].padStart( 9, ' ' ) + " = " + parseTime(tests[i]) );
}

answered 2010-10-22T15:29:16.520

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