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Detect any new DOM Element by its CSS Selector, then trigger a function. Includes Promise- & Callback interface. Based on ES6 MutationObserver. Ships legacy waitForKeyElements interface, too.
此脚本不应直接安装。它是供其他脚本使用的外部库，要使用该库请加入元指令 // @require https://update.greasyfork.icu/scripts/374849/1060689/Library%20%7C%20onElementReady%20ES7.js
// ==UserScript==
// @name Library: onElementReady ES7
// @namespace org.sidneys.userscripts
// @homepage https://gist.githubusercontent.com/sidneys/ee7a6b80315148ad1fb6847e72a22313/raw/
// @version 0.8.1
// @description Detect any new DOM Element by its CSS Selector, then trigger a function. Includes Promise- & Callback interface. Based on ES6 MutationObserver. Ships legacy waitForKeyElements interface, too.
// @author sidneys
// @icon https://i.imgur.com/nmbtzlX.png
// @match *://*/*
// ==/UserScript==
/**
* ESLint
* @exports
*/
/* exported onElementReady, waitForKeyElements */
/**
* @private
*
* Query for new DOM nodes matching a specified selector.
*
* @param {String} selector - CSS Selector
* @param {function=} callback - Callback
*/
let queryForElements = (selector, callback) => {
// console.debug('queryForElements', 'selector:', selector)
// Remember already-found elements via this attribute
const attributeName = 'was-queried'
// Search for elements by selector
let elementList = document.querySelectorAll(selector) || []
elementList.forEach((element) => {
if (element.hasAttribute(attributeName)) { return }
element.setAttribute(attributeName, 'true')
callback(element)
})
}
/**
* @public
*
* Wait for Elements with a given CSS selector to enter the DOM.
* Returns a Promise resolving with new Elements, and triggers a callback for every Element.
*
* @param {String} selector - CSS Selector
* @param {Boolean=} findOnce - Stop querying after first successful pass
* @param {function=} callback - Callback with Element
* @returns {Promise<Element>} - Resolves with Element
*/
let onElementReady = (selector, findOnce = false, callback = () => {}) => {
// console.debug('onElementReady', 'findOnce:', findOnce)
return new Promise((resolve) => {
// Initial Query
queryForElements(selector, (element) => {
resolve(element)
callback(element)
})
// Continuous Query
const observer = new MutationObserver(() => {
// DOM Changes detected
queryForElements(selector, (element) => {
resolve(element)
callback(element)
})
if (findOnce) { observer.disconnect() }
})
// Observe DOM Changes
observer.observe(document.documentElement, {
attributes: false,
childList: true,
subtree: true
})
})
}
/**
* @public
* @deprecated
*
* waitForKeyElements Polyfill
*
* @param {String} selector - CSS selector of elements to search / monitor ('.comment')
* @param {function} callback - Callback executed on element detection (called with element as argument)
* @param {Boolean=} findOnce - Stop lookup after the last currently available element has been found
* @returns {Promise<Element>} - Element
*/
let waitForKeyElements = (selector, callback, findOnce) => onElementReady(selector, findOnce, callback)