metadataValidation.js

(function($) {
    $(window).adaptTo("foundation-registry").register("foundation.validation.validator", {

        selector: '[name="./jcr:content/metadata/dc:title"]',
        validate: function(element) {

            const wrapper = $(element).parents().eq(1);

            // Apply only if schema is wknd-default
            if(!wrapper 
                || !wrapper.attr('data-path') 
                || !wrapper.attr('data-path').startsWith('/conf/global/settings/dam/adminui-extension/metadataschema/wknd-default')) return;

            // Min 3 characters, first being capital letter, others being alphabetical characters
            const validationRegex = /^[A-Z][a-zA-Z]{2,}$/;

            if (!validationRegex.test(element.value)) {
                return Granite.I18n.get('This field must be at least 3 characters long, begin with a capital letter and contain only alphabetic characters');
            }
        }
    });
})(Granite.$);