How to use the language-subtag-registry/data/json/registry.filter function in language-subtag-registry

test = function(description) {
			return query.test(description);
		};

	// If the query is all lowercase, make a case-insensitive match.
	} else if (query.toLowerCase() === query) {
		test = function(description) {
			return -1 !== description.toLowerCase().indexOf(query);
		};
	} else {
		test = function(description) {
			return -1 !== description.indexOf(query);
		};
	}

	return registry.filter(function(record) {
		if (!record.Subtag && !all) {
			return false;
		}

		return record.Description.some(test);

	// Sort by matched description string length.
	// This is a quick way to push precise matches towards the top.
	}).sort(function(a, b) {
		return Math.min.apply(Math, a.Description.filter(test).map(function(description) {
			return description.length;
		})) - Math.min.apply(Math, b.Description.filter(test).map(function(description) {
			return description.length;
		}));
	}).map(function(record) {
		if (record.Subtag) {