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解决js函数闭包内存泄露问题的办法

时间:2024-3-2 02:36     作者:韩俊     分类: Javascript


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

原始代码:

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()())

优化后的代码:

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()())

稍微复杂一点的例子:

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()()());

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:

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()()());

以上就是为大家分享的解决方法,希望对大家的学习有所帮助。

标签: javascript

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