JavaScript regex validation issue with time format

Question

I try to validate a time valie with the following script but the second value does not validate for some reason. Is there anything wrong on my script ?

var timeFormat      =   /^([0-9]{2})\:([0-9]{2})$/g;
var time_one        =   '00:00';
var time_two        =   '15:20';

if(timeFormat.test(time_one) == false)
{
    console.log('Time one is wrong');
}
else if(timeFormat.test(time_two) == false)
{
    console.log('Time two is wrong');
}

The above script returns always the Time two is wrong in my console. Also I have try to set the value of the time_two to '00:00' but again does not validate.

Is my regex wrong ?

NOTE : I also have try the following regex, but still with the same effect:

var timeFormat      =    /(\d{2}\:\d{2})/g;

Thanks every one for tha response !! :) – KodeFor.Me Sep 11 '13 at 08:29 — KodeFor.Me, Sep 11 '13 at 08:29

score 11 · Accepted Answer · answered Sep 11 '13 at 08:27

11

I think it comes from the "global" flag, try this instead :

var timeFormat = /^([0-9]{2})\:([0-9]{2})$/;

answered Sep 11 '13 at 08:27

See http://stackoverflow.com/questions/1520800/why-regexp-with-global-flag-in-javascript-give-wrong-results – alecxe Sep 11 '13 at 08:28
1

Yes, also try `/^\d\d:\d\d$/`. – elclanrs Sep 11 '13 at 08:29
1

@wared thanks for your answer, that was the issue, now working normaly. I will up vote your answer in < 10'' :) – KodeFor.Me Sep 11 '13 at 08:30
Good answer, but will allow invalid time values, such as 99:99. – Michael L. Mar 26 '14 at 22:36

score 1 · Answer 2 · answered Sep 11 '13 at 08:29

1

test will progress a global regexp by one match, and rewind when it gets to the end of the string.

var timeFormat      =   /^([0-9]{2})\:([0-9]{2})$/g;
var time_one        =   '00:00';

timeFormat.test(time_one)  // => true   finds 00:00
timeFormat.test(time_one)  // => false  no more matches
timeFormat.test(time_one)  // => true   restarts and finds 00:00 again

So you need to lose the g flag in your scenario.

answered Sep 11 '13 at 08:29

Amadan

191,408
23
240
301

@Amadan You were a member of FlashFrance right ? :-) – Sep 16 '17 at 06:18

score 1 · Answer 3 · answered Mar 26 '14 at 22:34

May I propose the following options:

/^[01]?\d:[0-5]\d( (am|pm))?$/i  // matches non-military time, e.g. 11:59 pm

/^[0-2]\d:[0-5]\d$/              // matches only military time, e.g. 23:59

/^[0-2]?\d:[0-5]\d( (am|pm))?$/i // matches either, but allows invalid values 
                                 // such as 23:59 pm

score 0 · Answer 4 · answered Oct 10 '18 at 12:36

0

Simple with

/^([01]\d|2[0-3]):?([0-5]\d)$/

output:

12:12 -> OK
00:00 -> OK
23:59 -> OK
24:00 -> NG
12:60 -> NG
9:40 -> NG

Demo: https://regexr.com/40vuj

answered Oct 10 '18 at 12:36

Tính Ngô Quang

4,400
1
33
33

JavaScript regex validation issue with time format

4 Answers4