Regular expression timezone

Question

I need a regular expression for valid time zone, tried the following one.
But I'm not sure about it.
Please help me to find out anything wrong in the following regular expression.

Edited:

Here colon and minutes are optional. how can i change it to mandatory.
If there is no minutes user should input 00 (+05:00). Please help me to solve this issue.

var chkzone = "+05:30"
if(chkzone .match(/^(Z|[+-](?:2[0-3]|[01]?[0-9])(?::?(?:[0-5]?[0-9]))?)$/))
{
    alert('works out');
}
else
{
    alert("Time zone wrong")
}

Answer 1

The following regex matches timezones with mandatory double digit hours/minutes, or the letter Z:

/^(?:Z|[+-](?:2[0-3]|[01][0-9]):[0-5][0-9])$/

Explanation:

^            # Start of string
(?:          # Match the following non-capturing group:
 Z           # Either a literal Z
|            # or
 [+-]        # a plus or minus sign
 (?:         # followed by this non-capturing group:
  2[0-3]     # Either a number between 20 and 23
 |           # or
  [01][0-9]  # a number between 00 and 19
 )           # End of inner non-capturing group
 :           # Match a literal colon
 [0-5][0-9]  # Match a number between 00 and 59
)            # End of outer non-capturing group
$            # End of string

See it live on regex101.com.