解决js函数闭包内存泄露问题的办法

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()()());

以上是 解决js函数闭包内存泄露问题的办法 的全部内容, 来源链接: utcz.com/z/314884.html

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