| <!doctype html> |
| <!-- |
| @license |
| Copyright (c) 2016 The Polymer Project Authors. All rights reserved. |
| This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt |
| The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt |
| The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt |
| Code distributed by Google as part of the polymer project is also |
| subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt |
| --> |
| <link rel="import" href="../polymer/polymer.html"> |
| |
| <script> |
| (function() { |
| 'use strict'; |
| |
| var p = Element.prototype; |
| var matches = p.matches || p.matchesSelector || p.mozMatchesSelector || |
| p.msMatchesSelector || p.oMatchesSelector || p.webkitMatchesSelector; |
| |
| Polymer.IronFocusablesHelper = { |
| |
| /** |
| * Returns a sorted array of tabbable nodes, including the root node. |
| * It searches the tabbable nodes in the light and shadow dom of the chidren, |
| * sorting the result by tabindex. |
| * @param {!Node} node |
| * @return {Array<HTMLElement>} |
| */ |
| getTabbableNodes: function(node) { |
| var result = []; |
| // If there is at least one element with tabindex > 0, we need to sort |
| // the final array by tabindex. |
| var needsSortByTabIndex = this._collectTabbableNodes(node, result); |
| if (needsSortByTabIndex) { |
| return this._sortByTabIndex(result); |
| } |
| return result; |
| }, |
| |
| /** |
| * Returns if a element is focusable. |
| * @param {!HTMLElement} element |
| * @return {boolean} |
| */ |
| isFocusable: function(element) { |
| // From http://stackoverflow.com/a/1600194/4228703: |
| // There isn't a definite list, it's up to the browser. The only |
| // standard we have is DOM Level 2 HTML https://www.w3.org/TR/DOM-Level-2-HTML/html.html, |
| // according to which the only elements that have a focus() method are |
| // HTMLInputElement, HTMLSelectElement, HTMLTextAreaElement and |
| // HTMLAnchorElement. This notably omits HTMLButtonElement and |
| // HTMLAreaElement. |
| // Referring to these tests with tabbables in different browsers |
| // http://allyjs.io/data-tables/focusable.html |
| |
| // Elements that cannot be focused if they have [disabled] attribute. |
| if (matches.call(element, 'input, select, textarea, button, object')) { |
| return matches.call(element, ':not([disabled])'); |
| } |
| // Elements that can be focused even if they have [disabled] attribute. |
| return matches.call(element, |
| 'a[href], area[href], iframe, [tabindex], [contentEditable]'); |
| }, |
| |
| /** |
| * Returns if a element is tabbable. To be tabbable, a element must be |
| * focusable, visible, and with a tabindex !== -1. |
| * @param {!HTMLElement} element |
| * @return {boolean} |
| */ |
| isTabbable: function(element) { |
| return this.isFocusable(element) && |
| matches.call(element, ':not([tabindex="-1"])') && |
| this._isVisible(element); |
| }, |
| |
| /** |
| * Returns the normalized element tabindex. If not focusable, returns -1. |
| * It checks for the attribute "tabindex" instead of the element property |
| * `tabIndex` since browsers assign different values to it. |
| * e.g. in Firefox `<div contenteditable>` has `tabIndex = -1` |
| * @param {!HTMLElement} element |
| * @return {!number} |
| * @private |
| */ |
| _normalizedTabIndex: function(element) { |
| if (this.isFocusable(element)) { |
| var tabIndex = element.getAttribute('tabindex') || 0; |
| return Number(tabIndex); |
| } |
| return -1; |
| }, |
| |
| /** |
| * Searches for nodes that are tabbable and adds them to the `result` array. |
| * Returns if the `result` array needs to be sorted by tabindex. |
| * @param {!Node} node The starting point for the search; added to `result` |
| * if tabbable. |
| * @param {!Array<HTMLElement>} result |
| * @return {boolean} |
| * @private |
| */ |
| _collectTabbableNodes: function(node, result) { |
| // If not an element or not visible, no need to explore children. |
| if (node.nodeType !== Node.ELEMENT_NODE || !this._isVisible(node)) { |
| return false; |
| } |
| var element = /** @type {HTMLElement} */ (node); |
| var tabIndex = this._normalizedTabIndex(element); |
| var needsSortByTabIndex = tabIndex > 0; |
| if (tabIndex >= 0) { |
| result.push(element); |
| } |
| |
| // In ShadowDOM v1, tab order is affected by the order of distrubution. |
| // E.g. getTabbableNodes(#root) in ShadowDOM v1 should return [#A, #B]; |
| // in ShadowDOM v0 tab order is not affected by the distrubution order, |
| // in fact getTabbableNodes(#root) returns [#B, #A]. |
| // <div id="root"> |
| // <!-- shadow --> |
| // <slot name="a"> |
| // <slot name="b"> |
| // <!-- /shadow --> |
| // <input id="A" slot="a"> |
| // <input id="B" slot="b" tabindex="1"> |
| // </div> |
| // TODO(valdrin) support ShadowDOM v1 when upgrading to Polymer v2.0. |
| var children; |
| if (element.localName === 'content') { |
| children = Polymer.dom(element).getDistributedNodes(); |
| } else { |
| // Use shadow root if possible, will check for distributed nodes. |
| children = Polymer.dom(element.root || element).children; |
| } |
| for (var i = 0; i < children.length; i++) { |
| // Ensure method is always invoked to collect tabbable children. |
| var needsSort = this._collectTabbableNodes(children[i], result); |
| needsSortByTabIndex = needsSortByTabIndex || needsSort; |
| } |
| return needsSortByTabIndex; |
| }, |
| |
| /** |
| * Returns false if the element has `visibility: hidden` or `display: none` |
| * @param {!HTMLElement} element |
| * @return {boolean} |
| * @private |
| */ |
| _isVisible: function(element) { |
| // Check inline style first to save a re-flow. If looks good, check also |
| // computed style. |
| var style = element.style; |
| if (style.visibility !== 'hidden' && style.display !== 'none') { |
| style = window.getComputedStyle(element); |
| return (style.visibility !== 'hidden' && style.display !== 'none'); |
| } |
| return false; |
| }, |
| |
| /** |
| * Sorts an array of tabbable elements by tabindex. Returns a new array. |
| * @param {!Array<HTMLElement>} tabbables |
| * @return {Array<HTMLElement>} |
| * @private |
| */ |
| _sortByTabIndex: function(tabbables) { |
| // Implement a merge sort as Array.prototype.sort does a non-stable sort |
| // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort |
| var len = tabbables.length; |
| if (len < 2) { |
| return tabbables; |
| } |
| var pivot = Math.ceil(len / 2); |
| var left = this._sortByTabIndex(tabbables.slice(0, pivot)); |
| var right = this._sortByTabIndex(tabbables.slice(pivot)); |
| return this._mergeSortByTabIndex(left, right); |
| }, |
| |
| /** |
| * Merge sort iterator, merges the two arrays into one, sorted by tab index. |
| * @param {!Array<HTMLElement>} left |
| * @param {!Array<HTMLElement>} right |
| * @return {Array<HTMLElement>} |
| * @private |
| */ |
| _mergeSortByTabIndex: function(left, right) { |
| var result = []; |
| while ((left.length > 0) && (right.length > 0)) { |
| if (this._hasLowerTabOrder(left[0], right[0])) { |
| result.push(right.shift()); |
| } else { |
| result.push(left.shift()); |
| } |
| } |
| |
| return result.concat(left, right); |
| }, |
| |
| /** |
| * Returns if element `a` has lower tab order compared to element `b` |
| * (both elements are assumed to be focusable and tabbable). |
| * Elements with tabindex = 0 have lower tab order compared to elements |
| * with tabindex > 0. |
| * If both have same tabindex, it returns false. |
| * @param {!HTMLElement} a |
| * @param {!HTMLElement} b |
| * @return {boolean} |
| * @private |
| */ |
| _hasLowerTabOrder: function(a, b) { |
| // Normalize tabIndexes |
| // e.g. in Firefox `<div contenteditable>` has `tabIndex = -1` |
| var ati = Math.max(a.tabIndex, 0); |
| var bti = Math.max(b.tabIndex, 0); |
| return (ati === 0 || bti === 0) ? bti > ati : ati > bti; |
| } |
| }; |
| })(); |
| </script> |
