Prepend URL scheme (http/https) to value saved when submitting a listing in WP Job Manager (if missing in field value filled out by user)

functions.php

<?php

add_filter( 'job_manager_get_posted_fields', 'smyles_set_url_scheme_if_not_exists', 10, 2 );

function smyles_set_url_scheme_if_not_exists( $values, $fields ){

	// Enter any Job, Company, or Resume fields you want to make sure have http or https in the field value before being saved
	$url_fields = array( 'job_field_with_url', 'resume_field_with_url' );
	// Set default scheme to http://
	$scheme = 'http://';

	foreach( (array) $values as $group_key => $meta_keys ){

		foreach( (array) $meta_keys as $meta_key => $meta_value ){

			// If not one of our URL fields, or has no value, continue to next
			if ( ! in_array( $meta_key, $url_fields ) || empty( $meta_value ) ) {
				continue;
			}

			// If already has valid scheme, continue to next
			if( parse_url( $meta_value, PHP_URL_SCHEME ) !== null ){
				continue;
			}

			// Make sure to remove // from front of value if set (means value looks like //somedomain.com/something)
			$value = substr( $meta_value, 0, 2 ) === '//' ? substr( $meta_value, 2 ) : $meta_value;
			// Prepend scheme to front of field value
			$values[ $group_key ][ $meta_key ] = $scheme . $value;
		}

	}

	return $values;
}