Reformat string containing uk postcode using regex

Question

How can I format a string using Javascript to match a regex?

I am using UK postcodes which could match any of the following

N1 3LD
EC1A 3AD
GU34 8RR

I have the following regex which validates a string correctly, but I am unsure how to use the regex as a mask to format EC1A3AD to EC1A 3AD / GU348RR to GU34 8RR / N13LD to N1 3LD.

My regex is /^[A-Za-z]{1,2}[0-9A-Za-z]{1,2}[ ]?[0-9]{0,1}[A-Za-z]{2}$/

Thank you

Answer 1

If you use the regular expression /^([A-Z]{1,2}\d{1,2}[A-Z]?)\s*(\d[A-Z]{2})$/ you can extract the two parts of the postcode and reassemble them with an intervening space.

var list = ['N13LD', 'EC1A3AD', 'GU348RR'];

for (var i = 0; i < list.length; i++) {
  var parts = list[i].match(/^([A-Z]{1,2}\d{1,2}[A-Z]?)\s*(\d[A-Z]{2})$/);
  parts.shift();
  alert(parts.join(' '));
}

output

N1 3LD
EC1A 3AD
GU34 8RR