UK Postcode in JS
Match UK postcodes in the common outward + inward format (e.g. SW1A 1AA, EC1V 9LB).
Try it in the JS tester →Pattern
regexJS
[A-Z]{1,2}\d[A-Z\d]? ?\d[A-Z]{2} (flags: gi)JavaScript / ECMAScript code
jsJavaScript
const re = new RegExp("[A-Z]{1,2}\\d[A-Z\\d]? ?\\d[A-Z]{2}", "gi");
const input = "SW1A 1AA";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));Uses `String.prototype.matchAll` for global iteration (Node 12+ / all modern browsers).
How the pattern works
1–2 letters, 1 digit, optional letter/digit, optional space, 1 digit, 2 letters. Case-insensitive flag handles lower and mixed case input.
Examples
Input
SW1A 1AAMatches
SW1A 1AA
Input
EC1V 9LBMatches
EC1V 9LB
Input
B33 8THMatches
B33 8TH