☰

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 2016-05-01 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/5679/122976/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.   function throttle(func) {
  14.     var now = Date.now();
  15.     clearTimeout(queuedCall);
  16.     // less than 100ms since last mutation
  17.     if(now - lastMutation < 100) {
  18.       // 500ms or more since last query
  19.       if(now - lastCall >= 500) {
  20.         func();
  21.       } else {
  22.         queuedCall = setTimeout(func, 100);
  23.       }
  24.     } else {
  25.       func();
  26.     }
  27.     lastMutation = now;
  28.   }
  29.   function findElem(sel) {
  30.     lastCall = Date.now();
  31.     var found = [].filter.call(document.querySelectorAll(sel), function(elem) {
  32.       return elem.dataset[id] !== 'y';
  33.     });
  34.     if(found.length > 0) {
  35.       if(stopLooking) {
  36.         type === 'M' ? tick.disconnect() : clearInterval(tick);
  37.       }
  38.       found.forEach(function(elem) {
  39.         elem.dataset[id] = 'y';
  40.         action(elem);
  41.       });
  42.     }
  43.   }
  44.   if(type === 'M') {
  45.     tick = new MutationObserver(throttle.bind(null, findElem.bind(null, sel)));
  46.     tick.observe(document.body, { subtree: true, childList: true });
  47.   } else {
  48.     tick = setInterval(findElem.bind(null, sel), 300);
  49.   }
  50.   findElem(sel);
  51.   return {
  52.     type: type,
  53.     stop: function() {
  54.       if(type === 'M') {
  55.         tick.disconnect();
  56.       } else {
  57.         clearInterval(tick);
  58.       }
  59.     }
  60.   };
  61. }
  62. /**
  63. * @param regex - should match the site you're waiting for
  64. * @param action - the callback that will be executed when a matching url is visited
  65. * @param stopLooking - if true the function will stop waiting for another url match after the first match
  66. */
  67. function waitForUrl(regex, action, stopLooking) {
  68.   function checkUrl(urlTest) {
  69.     var url = window.location.href;
  70.     if(url !== lastUrl && urlTest(url)) {
  71.       if(stopLooking) {
  72.         clearInterval(tick);
  73.       }
  74.       lastUrl = url;
  75.       action();
  76.     }
  77.     lastUrl = url;
  78.   }
  79.   var urlTest = (typeof regex === 'function' ? regex : regex.test.bind(regex)),
  80.       tick = setInterval(checkUrl.bind(null, urlTest), 300),
  81.       lastUrl;
  82.   checkUrl(urlTest);
  83.   return tick;
  84. }