几个闭包内存泄漏的优化方案！

来源：互联网发布：mac打印6寸相纸编辑：程序博客网时间：2024/05/16 19:36

本文通过举例，由浅入深的讲解了解决js函数闭包内存泄露问题的办法，分享给大家供大家参考，具体内容如下：

原代码：

<span style="font-size:14px;">function Cars(){    this.name = "Benz";    this.color = ["white","black"];  }  Cars.prototype.sayColor = function(){    var outer = this;    return function(){      return outer.color    };  };  var instance = new Cars();  console.log(instance.sayColor()())</span>

优化后：

<span style="font-size:14px;">function Cars(){    this.name = "Benz";    this.color = ["white","black"];  }  Cars.prototype.sayColor = function(){    var outerColor = this.color; //保存一个副本到变量中    return function(){      return outerColor; //应用这个副本    };    outColor = null; //释放内存  };  var instance = new Cars();  console.log(instance.sayColor()())</span>

举例：

<span style="font-size:14px;">function inheritPrototype(subType,superType){    var prototype = Object(superType.prototype);    prototype.constructor = subType;    subType.prototype = prototype;  }  function Cars(){    this.name = "Benz";    this.color = ["white","black"];  }  Cars.prototype.sayColor = function(){    var outer = this;    return function(){      return outer.color;    };  };  function Car(){    Cars.call(this);    this.number = [321,32];  }  inheritPrototype(Car,Cars);  Car.prototype.sayNumber = function(){    var outer = this;    return function(){      return function(){        return outer.number[outer.number.length - 1];      }    };  };  var instance = new Car();  console.log(instance.sayNumber()()());</span>

首先，该例子组合使用了构造函数模式和原型模式创建Cars 对象，并用了寄生组合式继承模式来创建Car 对象并从Cars 对象获得属性和方法的继承；

其次，建立一个名为instance 的Car 对象的实例；instance 实例包含了sayColor 和sayNumber 两种方法；

最后，两种方法中，前者使用了一个闭包，后者使用了两个闭包，并对其this 进行修改使其能够访问到this.color 和this.number。

这里存在内存泄露问题，优化后的代码如下：

<span style="font-size:14px;">function inheritPrototype(subType,superType){    var prototype = Object(superType.prototype);    prototype.constructor = subType;    subType.prototype = prototype;  }  function Cars(){    this.name = "Benz";    this.color = ["white","black"];  }  Cars.prototype.sayColor = function(){    var outerColor = this.color; //这里    return function(){      return outerColor; //这里    };    this = null; //这里  };  function Car(){    Cars.call(this);    this.number = [321,32];  }  inheritPrototype(Car,Cars);  Car.prototype.sayNumber = function(){    var outerNumber = this.number; //这里    return function(){      return function(){        return outerNumber[outerNumber.length - 1]; //这里      }    };    this = null; //这里  };  var instance = new Car();  console.log(instance.sayNumber()()());</span>

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