Set maxlength for checkout postcode field in WooCommerce - php

Question

I'm trying to delete or increase the default maxlength (nowadays set to 4) on a WordPress site I developed using Woocommerce.
Up to now I've tried all these functions on my childtheme's functions.php
#OPTION 1
function wpse215677_checkout_fields ( $fields ) {
$fields['postcode']['maxlength'] = 5;
return $fields;
}
add_filter('woocommerce_default_address_fields', 'wpse215677_checkout_fields');
#OPTION 2 - WITH AND WITHOUT ['custom_attributes']
add_filter( 'woocommerce_checkout_fields' , 'my_override_checkout_fields');
function my_override_checkout_fields( $fields ) {
$fields['billing']['postcode']['custom_attributes']['maxlength'] = 5;
$fields['billing']['billing_postcode']['custom_attributes']['maxlength'] = 5;
return $fields;
}
#OPTION 3 - WITH AND WITHOUT ['custom_attributes']
function my_wc_custom_billing_fields( $fields ) {
$fields['billing_postcode']['custom_attributes']['maxlength'] = 5;
return $fields;
}
add_filter( 'woocommerce_billing_fields', 'my_wc_custom_billing_fields' );
function my_wc_custom_shipping_fields( $fields ) {
$fields['shipping_postcode']['custom_attributes']['maxlength'] = 5;
return $fields;
}
add_filter( 'woocommerce_shipping_fields', 'my_wc_custom_shipping_fields' );
All of them worked fine on the cart calculator (now I can write any number over 4) but when I go to the checkout page and try to write a number over 4 characters on the postcode (shipping or billing), the input still remains with a maxlength of 4 (I've inspected it with Chrome's tools).
Is there any way I can overwrite the entire input on the checkout to allow me to write more than 4 characters on this input?
Or am i doing something wrong with these functions and that is why they are not working on the checkout page?

Answer 1

One way is to do it via jQuery, although the code you have already posted here works without any problems
function action_wp_footer() {
// Returns true on the checkout page, when false, return
if ( ! is_checkout() ) return;
?>
<script>
jQuery(document).ready(function($){
$( '#billing_postcode' ).attr( 'maxlength', '5' );
$( '#shipping_postcode' ).attr( 'maxlength', '5' );
});
</script>
<?php
}
add_action( 'wp_footer', 'action_wp_footer' );