{"version":3,"file":"skip-link.bundle.js","sources":["../../../../src/govuk/common/index.mjs","../../../../src/govuk/errors/index.mjs","../../../../src/govuk/govuk-frontend-component.mjs","../../../../src/govuk/components/skip-link/skip-link.mjs"],"sourcesContent":["/**\n * Common helpers which do not require polyfill.\n *\n * IMPORTANT: If a helper require a polyfill, please isolate it in its own module\n * so that the polyfill can be properly tree-shaken and does not burden\n * the components that do not need that helper\n */\n\n/**\n * Config flattening function\n *\n * Takes any number of objects, flattens them into namespaced key-value pairs,\n * (e.g. \\{'i18n.showSection': 'Show section'\\}) and combines them together, with\n * greatest priority on the LAST item passed in.\n *\n * @internal\n * @param {...{ [key: string]: unknown }} configObjects - Config object to merge\n * @returns {{ [key: string]: unknown }} A flattened object of key-value pairs.\n */\nexport function mergeConfigs(...configObjects) {\n /**\n * Function to take nested objects and flatten them to a dot-separated keyed\n * object. Doing this means we don't need to do any deep/recursive merging of\n * each of our objects, nor transform our dataset from a flat list into a\n * nested object.\n *\n * @internal\n * @param {{ [key: string]: unknown }} configObject - Deeply nested object\n * @returns {{ [key: string]: unknown }} Flattened object with dot-separated keys\n */\n function flattenObject(configObject) {\n // Prepare an empty return object\n /** @type {{ [key: string]: unknown }} */\n const flattenedObject = {}\n\n /**\n * Our flattening function, this is called recursively for each level of\n * depth in the object. At each level we prepend the previous level names to\n * the key using `prefix`.\n *\n * @internal\n * @param {Partial<{ [key: string]: unknown }>} obj - Object to flatten\n * @param {string} [prefix] - Optional dot-separated prefix\n */\n function flattenLoop(obj, prefix) {\n for (const [key, value] of Object.entries(obj)) {\n const prefixedKey = prefix ? `${prefix}.${key}` : key\n\n // If the value is a nested object, recurse over that too\n if (value && typeof value === 'object') {\n flattenLoop(value, prefixedKey)\n } else {\n // Otherwise, add this value to our return object\n flattenedObject[prefixedKey] = value\n }\n }\n }\n\n // Kick off the recursive loop\n flattenLoop(configObject)\n return flattenedObject\n }\n\n // Start with an empty object as our base\n /** @type {{ [key: string]: unknown }} */\n const formattedConfigObject = {}\n\n // Loop through each of the passed objects\n for (const configObject of configObjects) {\n const obj = flattenObject(configObject)\n\n // Push their keys one-by-one into formattedConfigObject. Any duplicate\n // keys will override the existing key with the new value.\n for (const [key, value] of Object.entries(obj)) {\n formattedConfigObject[key] = value\n }\n }\n\n return formattedConfigObject\n}\n\n/**\n * Extracts keys starting with a particular namespace from a flattened config\n * object, removing the namespace in the process.\n *\n * @internal\n * @param {{ [key: string]: unknown }} configObject - The object to extract key-value pairs from.\n * @param {string} namespace - The namespace to filter keys with.\n * @returns {{ [key: string]: unknown }} Flattened object with dot-separated key namespace removed\n */\nexport function extractConfigByNamespace(configObject, namespace) {\n /** @type {{ [key: string]: unknown }} */\n const newObject = {}\n\n for (const [key, value] of Object.entries(configObject)) {\n // Split the key into parts, using . as our namespace separator\n const keyParts = key.split('.')\n\n // Check if the first namespace matches the configured namespace\n if (keyParts[0] === namespace) {\n // Remove the first item (the namespace) from the parts array,\n // but only if there is more than one part (we don't want blank keys!)\n if (keyParts.length > 1) {\n keyParts.shift()\n }\n\n // Join the remaining parts back together\n const newKey = keyParts.join('.')\n\n // Add them to our new object\n newObject[newKey] = value\n }\n }\n\n return newObject\n}\n\n/**\n * Get hash fragment from URL\n *\n * Extract the hash fragment (everything after the hash) from a URL,\n * but not including the hash symbol\n *\n * @private\n * @param {string} url - URL\n * @returns {string | undefined} Fragment from URL, without the hash\n */\nexport function getFragmentFromUrl(url) {\n if (!url.includes('#')) {\n return undefined\n }\n\n return url.split('#').pop()\n}\n\n/**\n * Get GOV.UK Frontend breakpoint value from CSS custom property\n *\n * @private\n * @param {string} name - Breakpoint name\n * @returns {{ property: string, value?: string }} Breakpoint object\n */\nexport function getBreakpoint(name) {\n const property = `--govuk-frontend-breakpoint-${name}`\n\n // Get value from `` with breakpoints on CSS :root\n const value = window\n .getComputedStyle(document.documentElement)\n .getPropertyValue(property)\n\n return {\n property,\n value: value || undefined\n }\n}\n\n/**\n * Move focus to element\n *\n * Sets tabindex to -1 to make the element programmatically focusable,\n * but removes it on blur as the element doesn't need to be focused again.\n *\n * @private\n * @template {HTMLElement} FocusElement\n * @param {FocusElement} $element - HTML element\n * @param {object} [options] - Handler options\n * @param {function(this: FocusElement): void} [options.onBeforeFocus] - Callback before focus\n * @param {function(this: FocusElement): void} [options.onBlur] - Callback on blur\n */\nexport function setFocus($element, options = {}) {\n const isFocusable = $element.getAttribute('tabindex')\n\n if (!isFocusable) {\n $element.setAttribute('tabindex', '-1')\n }\n\n /**\n * Handle element focus\n */\n function onFocus() {\n $element.addEventListener('blur', onBlur, { once: true })\n }\n\n /**\n * Handle element blur\n */\n function onBlur() {\n options.onBlur?.call($element)\n\n if (!isFocusable) {\n $element.removeAttribute('tabindex')\n }\n }\n\n // Add listener to reset element on blur, after focus\n $element.addEventListener('focus', onFocus, { once: true })\n\n // Focus element\n options.onBeforeFocus?.call($element)\n $element.focus()\n}\n\n/**\n * Checks if GOV.UK Frontend is supported on this page\n *\n * Some browsers will load and run our JavaScript but GOV.UK Frontend\n * won't be supported.\n *\n * @internal\n * @param {HTMLElement | null} [$scope] - HTML element `
` checked for browser support\n * @returns {boolean} Whether GOV.UK Frontend is supported on this page\n */\nexport function isSupported($scope = document.body) {\n if (!$scope) {\n return false\n }\n\n return $scope.classList.contains('govuk-frontend-supported')\n}\n\n/**\n * Validate component config by schema\n *\n * @internal\n * @param {Schema} schema - Config schema\n * @param {{ [key: string]: unknown }} config - Component config\n * @returns {string[]} List of validation errors\n */\nexport function validateConfig(schema, config) {\n const validationErrors = []\n\n // Check errors for each schema\n for (const [name, conditions] of Object.entries(schema)) {\n const errors = []\n\n // Check errors for each schema condition\n for (const { required, errorMessage } of conditions) {\n if (!required.every((key) => !!config[key])) {\n errors.push(errorMessage) // Missing config key value\n }\n }\n\n // Check one condition passes or add errors\n if (name === 'anyOf' && !(conditions.length - errors.length >= 1)) {\n validationErrors.push(...errors)\n }\n }\n\n return validationErrors\n}\n\n/**\n * Schema for component config\n *\n * @typedef {object} Schema\n * @property {SchemaCondition[]} [anyOf] - List of schema conditions\n */\n\n/**\n * Schema condition for component config\n *\n * @typedef {object} SchemaCondition\n * @property {string[]} required - List of required config fields\n * @property {string} errorMessage - Error message when required config fields not provided\n */\n","/**\n * GOV.UK Frontend error\n *\n * A base class for `Error`s thrown by GOV.UK Frontend.\n *\n * It is meant to be extended into specific types of errors\n * to be thrown by our code.\n *\n * @example\n * ```js\n * class MissingRootError extends GOVUKFrontendError {\n * // Setting an explicit name is important as extending the class will not\n * // set a new `name` on the subclass. The `name` property is important\n * // to ensure intelligible error names even if the class name gets\n * // mangled by a minifier\n * name = \"MissingRootError\"\n * }\n * ```\n * @abstract\n */\nexport class GOVUKFrontendError extends Error {\n name = 'GOVUKFrontendError'\n}\n\n/**\n * Indicates that GOV.UK Frontend is not supported\n */\nexport class SupportError extends GOVUKFrontendError {\n name = 'SupportError'\n\n /**\n * Checks if GOV.UK Frontend is supported on this page\n *\n * @param {HTMLElement | null} [$scope] - HTML element `` checked for browser support\n */\n constructor($scope = document.body) {\n const supportMessage =\n 'noModule' in HTMLScriptElement.prototype\n ? 'GOV.UK Frontend initialised without `` from template `