зеркало из https://github.com/mozilla/gecko-dev.git
115 строки
3.4 KiB
JavaScript
115 строки
3.4 KiB
JavaScript
/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
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/* vim: set ts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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"use strict";
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this.EXPORTED_SYMBOLS = ["findCssSelector"];
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/**
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* Traverse getBindingParent until arriving upon the bound element
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* responsible for the generation of the specified node.
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* See https://developer.mozilla.org/en-US/docs/XBL/XBL_1.0_Reference/DOM_Interfaces#getBindingParent.
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*
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* @param {DOMNode} node
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* @return {DOMNode}
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* If node is not anonymous, this will return node. Otherwise,
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* it will return the bound element
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*
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*/
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function getRootBindingParent(node) {
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let parent;
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let doc = node.ownerDocument;
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if (!doc) {
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return node;
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}
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while ((parent = doc.getBindingParent(node))) {
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node = parent;
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}
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return node;
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}
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/**
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* Find the position of [element] in [nodeList].
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* @returns an index of the match, or -1 if there is no match
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*/
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function positionInNodeList(element, nodeList) {
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for (let i = 0; i < nodeList.length; i++) {
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if (element === nodeList[i]) {
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return i;
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}
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}
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return -1;
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}
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/**
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* Find a unique CSS selector for a given element
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* @returns a string such that ele.ownerDocument.querySelector(reply) === ele
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* and ele.ownerDocument.querySelectorAll(reply).length === 1
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*/
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const findCssSelector = function(ele) {
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ele = getRootBindingParent(ele);
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let document = ele.ownerDocument;
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if (!document || !document.contains(ele)) {
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throw new Error("findCssSelector received element not inside document");
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}
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let cssEscape = ele.ownerGlobal.CSS.escape;
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// document.querySelectorAll("#id") returns multiple if elements share an ID
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if (ele.id &&
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document.querySelectorAll("#" + cssEscape(ele.id)).length === 1) {
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return "#" + cssEscape(ele.id);
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}
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// Inherently unique by tag name
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let tagName = ele.localName;
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if (tagName === "html") {
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return "html";
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}
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if (tagName === "head") {
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return "head";
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}
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if (tagName === "body") {
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return "body";
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}
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// We might be able to find a unique class name
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let selector, index, matches;
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if (ele.classList.length > 0) {
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for (let i = 0; i < ele.classList.length; i++) {
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// Is this className unique by itself?
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selector = "." + cssEscape(ele.classList.item(i));
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matches = document.querySelectorAll(selector);
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if (matches.length === 1) {
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return selector;
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}
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// Maybe it's unique with a tag name?
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selector = cssEscape(tagName) + selector;
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matches = document.querySelectorAll(selector);
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if (matches.length === 1) {
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return selector;
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}
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// Maybe it's unique using a tag name and nth-child
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index = positionInNodeList(ele, ele.parentNode.children) + 1;
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selector = selector + ":nth-child(" + index + ")";
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matches = document.querySelectorAll(selector);
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if (matches.length === 1) {
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return selector;
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}
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}
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}
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// Not unique enough yet. As long as it's not a child of the document,
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// continue recursing up until it is unique enough.
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if (ele.parentNode !== document) {
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index = positionInNodeList(ele, ele.parentNode.children) + 1;
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selector = findCssSelector(ele.parentNode) + " > " +
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cssEscape(tagName) + ":nth-child(" + index + ")";
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}
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return selector;
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};
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