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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/5679/122961/Wait%20For%20Elements.js 

/**
* @param sel - the selector you want to wait for
* @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
* @param stopLooking - if true the function will stop looking for more elements after the first match
*/
function waitForElems(sel, action, stopLooking) {
  var tick;
  var id = 'fke' + Math.floor(Math.random() * 12345);
  var type = window.MutationObserver ? 'M' : 'S';
  var lastMutation = Date.now();
  var lastCall = Date.now();
  var queuedCall;
  function throttle(func) {
    var now = Date.now();
    clearTimeout(queuedCall);
    // less than 100ms since last mutation
    if(now - lastMutation < 100) {
      // 500ms or more since last query
      Util.log(now - lastCall);
      if(now - lastCall >= 500) {
        func();
      } else {
        queuedCall = setTimeout(func, 100);
      }
    } else {
      func();
    }
    lastMutation = now;
  }
  function findElem(sel) {
    lastCall = Date.now();
    var found = [].filter.call(document.querySelectorAll(sel), function(elem) {
      return elem.dataset[id] !== 'y';
    });
    if(found.length > 0) {
      if(stopLooking) {
        type === 'M' ? tick.disconnect() : clearInterval(tick);
      }
      found.forEach(function(elem) {
        elem.dataset[id] = 'y';
        action(elem);
      });
    }
  }
  if(type === 'M') {
    tick = new MutationObserver(throttle.bind(null, findElem.bind(null, sel)));
    tick.observe(document.body, { subtree: true, childList: true });
  } else {
    tick = setInterval(findElem.bind(null, sel), 300);
  }
  findElem(sel);
  return tick;
}
/**
* @param regex - should match the site you're waiting for
* @param action - the callback that will be executed when a matching url is visited
* @param stopLooking - if true the function will stop waiting for another url match after the first match
*/
function waitForUrl(regex, action, stopLooking) {
  function checkUrl(urlTest) {
    var url = window.location.href;
    if(url !== lastUrl && urlTest(url)) {
      if(stopLooking) {
        clearInterval(tick);
      }
      lastUrl = url;
      action();
    }
    lastUrl = url;
  }
  var urlTest = (typeof regex === 'function' ? regex : regex.test.bind(regex)),
      tick = setInterval(checkUrl.bind(null, urlTest), 300),
      lastUrl;
  checkUrl(urlTest);
  return tick;
}