Get outbound part of UK postcode using Twig (handy for Craft Commerce shipping rules)

postcodeCheck.twig

{# These are the valid UK postcode formats 
according to https://ideal-postcodes.co.uk/guides/uk-postcode-format #}

{% set zipCodes = [
'AA9A 9AA',
'A9A 9AA',
'A9 9AA',
'A99 9AA',
'AA9 9AA',
'AA99 9AA'
] %}



{% for zipCode in zipCodes %}
    {# Normalise zipcode, remove spaces, make uppercase
    Remove last 3 characters and return the remainder #}
    {{ zipCode }} - {{ zipCode|replace({' ':''})|upper|slice(0,-3) }}
{% endfor %}