replaceThing 闭包泄漏（A surprising JavaScript memory leak found at Meteor）

var run = function () {
  var str = new Array(1000000).join(‘*‘);
  var doSomethingWithStr = function () {
    if (str === ‘something‘)
      console.log("str was something");
  };
  doSomethingWithStr();
};
setInterval(run, 1000);

var run = function () {
  var str = new Array(1000000).join(‘*‘);
  var logIt = function () {
    console.log(‘interval‘);
  };
  setInterval(logIt, 100);
};
setInterval(run, 1000);

var run = function () {
  var str = new Array(1000000).join(‘*‘);
  var doSomethingWithStr = function () {
    if (str === ‘something‘)
      console.log("str was something");
  };
  doSomethingWithStr();
  var logIt = function () {
    console.log(‘interval‘);
  }
  setInterval(logIt, 100);
};
setInterval(run, 1000);

var theThing = null;
var replaceThing = function () {
  var originalThing = theThing;
  // Define a closure that references originalThing but doesn‘t ever actually get called.
//定义一个引用originalThing但实际上没有调用它的实例闭包
  // But because this closure exists, originalThing will be in the
  // lexical environment for all closures defined in replaceThing, instead of
  // being optimized out of it. If you remove this function, there is no leak.
//但是由于这个闭包的存在，originalThing将存于定义在replaceThing中的所有闭包的词法环境中，而不被优化，如果你移除 这个方法，就不会有泄漏
  var unused = function () {
    if (originalThing)
      console.log("hi");
  };
  theThing = {
    longStr: new Array(1000000).join(‘*‘),
    // While originalThing is theoretically accessible by this function, it
    // obviously doesn‘t use it. But because originalThing is part of the
    // lexical environment, someMethod will hold a reference to originalThing,
    // and so even though we are replacing theThing with something that has no
    // effective way to reference the old value of theThing, the old value
// will never get cleaned up!
//虽然originalThing理论上可以通过这函数（someMethod）访问，但显然没有使用它，但是由于originalThing是词法环境的一部分，someMethod将会保留一个引用指向originalThing，所以即使我们用非有效的方式替换旧的theThing值，但是旧值不会被清理。
    someMethod: function () {}
  };
  // If you add `originalThing = null` here, there is no leak.
//此处加originalThing = null不会有泄漏
};
setInterval(replaceThing, 1000);