☰

Wait For Elements

given a selector waits for elements to be inserted into the DOM and executes a callback for each match

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.cn-greasyfork.org/scripts/5679/250853/Wait%20For%20Elements.js 

  1. /**
  2.  * @param obj - {
  3.  *  sel: 'a',                    // the selector you want to wait for (optional)
  4.  *  context: document.body,      // scope of search for selector or mutations (optional, default document.body)
  5.  *  stop: true,                  // stop waiting after first result (optional, default false)
  6.  *  mode: 'M',                   // M to use mutation observer, S to use setInterval (optional, default M)
  7.  *  onchange: func,              // if using mode 'M' this function will be called whenever mutation handler triggers
  8.  *  onmatch: func,               // if selector is specified function will be called for each match with element as parameter
  9.  *  config: { attributes: true } // if using mode 'M' this object will override settings passed to mutation observer
  10.  * }
  11.  */
  12. function waitForElems(obj) {
  13.   var tick;
  14.   var id = 'fke' + Math.floor(Math.random() * 12345);
  15.   var type = window.MutationObserver ? (obj.mode || 'M') : 'S';
  16.   var lastMutation = Date.now();
  17.   var lastCall = Date.now();
  18.   var context = obj.context || document.body;
  19.   var sel = obj.sel;
  20.   var config = obj.config || {
  21.     subtree: true,
  22.     childList: true
  23.   };
  24.   var onChange = obj.onchange;
  25.   var queuedCall;
  26.  
  27.   function throttle(func) {
  28.     var now = Date.now();
  29.     clearTimeout(queuedCall);
  30.     // less than 100ms since last mutation
  31.     if (now - lastMutation < 100) {
  32.       // 500ms or more since last query
  33.       if (now - lastCall >= 500) {
  34.         func();
  35.       } else {
  36.         queuedCall = setTimeout(func, 100);
  37.       }
  38.     } else {
  39.       func();
  40.     }
  41.     lastMutation = now;
  42.   }
  43.  
  44.   function findElem(sel) {
  45.     lastCall = Date.now();
  46.     var found = [].filter.call(context.querySelectorAll(sel), function(elem) {
  47.       return elem.dataset[id] !== 'y';
  48.     });
  49.     if (found.length > 0) {
  50.       if (obj.stop) {
  51.         type === 'M' ? tick.disconnect() : clearInterval(tick);
  52.       }
  53.       found.forEach(function(elem) {
  54.         elem.dataset[id] = 'y';
  55.         obj.onmatch(elem);
  56.       });
  57.     }
  58.   }
  59.   if (type === 'M') {
  60.     tick = new MutationObserver(function() {
  61.       if (sel) throttle.call(null, findElem.bind(null, sel));
  62.       if (onChange) onChange.apply(this, arguments);
  63.     });
  64.     tick.observe(context, config);
  65.   } else {
  66.     tick = setInterval(findElem.bind(null, sel), 300);
  67.   }
  68.   if (sel) findElem(sel);
  69.   return {
  70.     type: type,
  71.     stop: function() {
  72.       if (type === 'M') {
  73.         tick.disconnect();
  74.       } else {
  75.         clearInterval(tick);
  76.       }
  77.     },
  78.     resume: function() {
  79.       if (type === 'M') {
  80.         tick.observe(context, config);
  81.       } else {
  82.         tick = setInterval(findElem.bind(null, sel), 300);
  83.       }
  84.     }
  85.   };
  86. }
  87. /**
  88.  * @param regex - should match the site you're waiting for
  89.  * @param action - the callback that will be executed when a matching url is visited
  90.  * @param stopLooking - if true the function will stop waiting for another url match after the first match
  91.  */
  92. function waitForUrl(regex, action, stopLooking) {
  93.   function checkUrl(urlTest) {
  94.     var url = window.location.href;
  95.     if (url !== lastUrl && urlTest(url)) {
  96.       if (stopLooking) {
  97.         clearInterval(tick);
  98.       }
  99.       lastUrl = url;
  100.       action();
  101.     }
  102.     lastUrl = url;
  103.   }
  104.   var urlTest = (typeof regex === 'function' ? regex : regex.test.bind(regex)),
  105.     tick = setInterval(checkUrl.bind(null, urlTest), 300),
  106.     lastUrl;
  107.   checkUrl(urlTest);
  108.   return tick;
  109. }