☰

Wait For Elements

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

当前为 2016-08-15 提交的版本，查看 最新版本。

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/5679/141779/Wait%20For%20Elements.js 

  1. /**
  2.  * @param sel - the selector you want to wait for
  3.  * @param action - the callback that will be executed when element/s matching the given selector are found, it is passed the array of found elements
  4.  * @param stopLooking - if true the function will stop looking for more elements after the first match
  5.  */
  6. function waitForElems(sel, action, stopLooking) {
  7.   var tick;
  8.   var id = 'fke' + Math.floor(Math.random() * 12345);
  9.   var type = window.MutationObserver ? 'M' : 'S';
  10.   var lastMutation = Date.now();
  11.   var lastCall = Date.now();
  12.   var queuedCall;
  13.  
  14.   function throttle(func) {
  15.     var now = Date.now();
  16.     clearTimeout(queuedCall);
  17.     // less than 100ms since last mutation
  18.     if (now - lastMutation < 100) {
  19.       // 500ms or more since last query
  20.       if (now - lastCall >= 500) {
  21.         func();
  22.       }
  23.       else {
  24.         queuedCall = setTimeout(func, 100);
  25.       }
  26.     }
  27.     else {
  28.       func();
  29.     }
  30.     lastMutation = now;
  31.   }
  32.  
  33.   function findElem(sel) {
  34.     lastCall = Date.now();
  35.     var found = [].filter.call(document.querySelectorAll(sel), function(elem) {
  36.       return elem.dataset[id] !== 'y';
  37.     });
  38.     if (found.length > 0) {
  39.       if (stopLooking) {
  40.         type === 'M' ? tick.disconnect() : clearInterval(tick);
  41.       }
  42.       found.forEach(function(elem) {
  43.         elem.dataset[id] = 'y';
  44.         action(elem);
  45.       });
  46.     }
  47.   }
  48.   if (type === 'M') {
  49.     tick = new MutationObserver(throttle.bind(null, findElem.bind(null, sel)));
  50.     tick.observe(document.body, {
  51.       subtree: true,
  52.       childList: true
  53.     });
  54.   }
  55.   else {
  56.     tick = setInterval(findElem.bind(null, sel), 300);
  57.   }
  58.   findElem(sel);
  59.   return {
  60.     type: type,
  61.     stop: function() {
  62.       if (type === 'M') {
  63.         tick.disconnect();
  64.       }
  65.       else {
  66.         clearInterval(tick);
  67.       }
  68.     }
  69.   };
  70. }
  71. /**
  72.  * @param regex - should match the site you're waiting for
  73.  * @param action - the callback that will be executed when a matching url is visited
  74.  * @param stopLooking - if true the function will stop waiting for another url match after the first match
  75.  */
  76. function waitForUrl(regex, action, stopLooking) {
  77.   function checkUrl(urlTest) {
  78.     var url = window.location.href;
  79.     if (url !== lastUrl && urlTest(url)) {
  80.       if (stopLooking) {
  81.         clearInterval(tick);
  82.       }
  83.       lastUrl = url;
  84.       action();
  85.     }
  86.     lastUrl = url;
  87.   }
  88.   var urlTest = (typeof regex === 'function' ? regex : regex.test.bind(regex)),
  89.     tick = setInterval(checkUrl.bind(null, urlTest), 300),
  90.     lastUrl;
  91.   checkUrl(urlTest);
  92.   return tick;
  93. }