govuk-frontend
Version:
GOV.UK Frontend contains the code you need to start building a user interface for government platforms and services.
218 lines (208 loc) • 7.42 kB
JavaScript
(function (global, factory) {
typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
typeof define === 'function' && define.amd ? define(['exports'], factory) :
(global = typeof globalThis !== 'undefined' ? globalThis : global || self, factory(global.GOVUKFrontend = global.GOVUKFrontend || {}));
})(this, (function (exports) { 'use strict';
function setFocus($element, options = {}) {
var _options$onBeforeFocu;
const isFocusable = $element.getAttribute('tabindex');
if (!isFocusable) {
$element.setAttribute('tabindex', '-1');
}
function onFocus() {
$element.addEventListener('blur', onBlur, {
once: true
});
}
function onBlur() {
var _options$onBlur;
(_options$onBlur = options.onBlur) == null || _options$onBlur.call($element);
if (!isFocusable) {
$element.removeAttribute('tabindex');
}
}
$element.addEventListener('focus', onFocus, {
once: true
});
(_options$onBeforeFocu = options.onBeforeFocus) == null || _options$onBeforeFocu.call($element);
$element.focus();
}
function isInitialised($root, moduleName) {
return $root instanceof HTMLElement && $root.hasAttribute(`data-${moduleName}-init`);
}
/**
* Checks if GOV.UK Frontend is supported on this page
*
* Some browsers will load and run our JavaScript but GOV.UK Frontend
* won't be supported.
*
* @param {HTMLElement | null} [$scope] - (internal) `<body>` HTML element checked for browser support
* @returns {boolean} Whether GOV.UK Frontend is supported on this page
*/
function isSupported($scope = document.body) {
if (!$scope) {
return false;
}
return $scope.classList.contains('govuk-frontend-supported');
}
function isArray(option) {
return Array.isArray(option);
}
function isObject(option) {
return !!option && typeof option === 'object' && !isArray(option);
}
function formatErrorMessage(Component, message) {
return `${Component.moduleName}: ${message}`;
}
/**
* @typedef ComponentWithModuleName
* @property {string} moduleName - Name of the component
*/
class GOVUKFrontendError extends Error {
constructor(...args) {
super(...args);
this.name = 'GOVUKFrontendError';
}
}
class SupportError extends GOVUKFrontendError {
/**
* Checks if GOV.UK Frontend is supported on this page
*
* @param {HTMLElement | null} [$scope] - HTML element `<body>` checked for browser support
*/
constructor($scope = document.body) {
const supportMessage = 'noModule' in HTMLScriptElement.prototype ? 'GOV.UK Frontend initialised without `<body class="govuk-frontend-supported">` from template `<script>` snippet' : 'GOV.UK Frontend is not supported in this browser';
super($scope ? supportMessage : 'GOV.UK Frontend initialised without `<script type="module">`');
this.name = 'SupportError';
}
}
class ElementError extends GOVUKFrontendError {
constructor(messageOrOptions) {
let message = typeof messageOrOptions === 'string' ? messageOrOptions : '';
if (isObject(messageOrOptions)) {
const {
component,
identifier,
element,
expectedType
} = messageOrOptions;
message = identifier;
message += element ? ` is not of type ${expectedType != null ? expectedType : 'HTMLElement'}` : ' not found';
if (component) {
message = formatErrorMessage(component, message);
}
}
super(message);
this.name = 'ElementError';
}
}
class InitError extends GOVUKFrontendError {
constructor(componentOrMessage) {
const message = typeof componentOrMessage === 'string' ? componentOrMessage : formatErrorMessage(componentOrMessage, `Root element (\`$root\`) already initialised`);
super(message);
this.name = 'InitError';
}
}
/**
* @import { ComponentWithModuleName } from '../common/index.mjs'
*/
class Component {
/**
* Returns the root element of the component
*
* @protected
* @returns {RootElementType} - the root element of component
*/
get $root() {
return this._$root;
}
constructor($root) {
this._$root = void 0;
const childConstructor = this.constructor;
if (typeof childConstructor.moduleName !== 'string') {
throw new InitError(`\`moduleName\` not defined in component`);
}
if (!($root instanceof childConstructor.elementType)) {
throw new ElementError({
element: $root,
component: childConstructor,
identifier: 'Root element (`$root`)',
expectedType: childConstructor.elementType.name
});
} else {
this._$root = $root;
}
childConstructor.checkSupport();
this.checkInitialised();
const moduleName = childConstructor.moduleName;
this.$root.setAttribute(`data-${moduleName}-init`, '');
}
checkInitialised() {
const constructor = this.constructor;
const moduleName = constructor.moduleName;
if (moduleName && isInitialised(this.$root, moduleName)) {
throw new InitError(constructor);
}
}
static checkSupport() {
if (!isSupported()) {
throw new SupportError();
}
}
}
/**
* @typedef ChildClass
* @property {string} moduleName - The module name that'll be looked for in the DOM when initialising the component
*/
/**
* @typedef {typeof Component & ChildClass} ChildClassConstructor
*/
Component.elementType = HTMLElement;
/**
* Skip link component
*
* @preserve
* @augments Component<HTMLAnchorElement>
*/
class SkipLink extends Component {
/**
* @param {Element | null} $root - HTML element to use for skip link
* @throws {ElementError} when $root is not set or the wrong type
* @throws {ElementError} when $root.hash does not contain a hash
* @throws {ElementError} when the linked element is missing or the wrong type
*/
constructor($root) {
var _this$$root$getAttrib;
super($root);
const hash = this.$root.hash;
const href = (_this$$root$getAttrib = this.$root.getAttribute('href')) != null ? _this$$root$getAttrib : '';
if (this.$root.origin !== window.location.origin || this.$root.pathname !== window.location.pathname) {
return;
}
const linkedElementId = hash.replace('#', '');
if (!linkedElementId) {
throw new ElementError(`Skip link: Target link (\`href="${href}"\`) has no hash fragment`);
}
const $linkedElement = document.getElementById(linkedElementId);
if (!$linkedElement) {
throw new ElementError({
component: SkipLink,
element: $linkedElement,
identifier: `Target content (\`id="${linkedElementId}"\`)`
});
}
this.$root.addEventListener('click', () => setFocus($linkedElement, {
onBeforeFocus() {
$linkedElement.classList.add('govuk-skip-link-focused-element');
},
onBlur() {
$linkedElement.classList.remove('govuk-skip-link-focused-element');
}
}));
}
}
SkipLink.elementType = HTMLAnchorElement;
SkipLink.moduleName = 'govuk-skip-link';
exports.SkipLink = SkipLink;
}));
//# sourceMappingURL=skip-link.bundle.js.map