We are often required to validate input fields. One field that is often neglected or relies heavily on users inputting data in the correct format is the UK postcode field. The format of the postcode is listed here http://www.govtalk.gov.uk/gdsc/html/frames/PostCode.htm.
We have a Regular Expression / Javascript solution that validates UK postcode formats. Briefly all valid formats are:
| Format | Example |
| AN NAA |
M1 1AA |
| ANN NAA |
M60 1NW |
| AAN NAA |
CR2 6XH |
| AANN NAA |
DN55 1PT |
| ANA NAA |
W1A 1HQ |
| AANA NAA |
EC1A 1BB |
The regex we use is:
/^([A-PR-UWYZ0-9][A-HK-Y0-9][AEHMNPRTVXY0-9]?[ABEHMNPRVWXY0-9]? {1,2}[0-9][ABD-HJLN-UW-Z]{2}|GIR 0AA)$/i
Or you could try this:
^((([A-PR-UWYZ][0-9])|([A-PR-UWYZ][0-9][0-9])|([A-PR-UWYZ][A-HK-Y][0-9])|([A-PR-UWYZ][A-HK-Y][0-9][0-9])
|([A-PR-UWYZ][0-9][A-HJKSTUW])|([A-PR-UWYZ][A-HK-Y][0-9][ABEHMNPRVWXY]))\s?([0-9][ABD-HJLNP-UW-Z]{2})|
(GIR)\s?(0AA))$
Simple and effective.
UDPATE 2009 This will only validate UPPERCASE input. You will need to upper your input before validating it.