Javascript构造函数有什么意义？

Please provide your thoughts with respect to Javascript only! I am aware of classes and classical inheritance but not at a great detail.

请提供您对Javascript的想法!我知道类和经典继承但不是很详细。

As far as I know, constructors are used as prototypes for other objects. For example, I could create a car constructor and give it objects such as hondaCivic, toyotaCamry, etc. Are there any other important things I should know about constructors?

据我所知,构造函数被用作其他对象的原型。例如,我可以创建一个汽车构造函数并为其提供诸如hondaCivic,toyotaCamry等对象。我还应该了解有关构造函数的其他重要事项吗?

Furthermore,

What is the purpose of a constructor, apart from what I have already stated?

除了我已经陈述的内容之外,构造函数的目的是什么?

What are the benefits / disadvantages of a constructor?

构造函数的好处/缺点是什么?

3 个解决方案

#1

A constructor is just a normal function. There is nothing special about it inherently.

构造函数只是一个普通的函数。它本身并没有什么特别之处。

All functions have a property called prototype.

所有函数都有一个名为prototype的属性。

If you write

如果你写

var myInstance = new MyFuction();

JavaScript does something special with your function when it executes it.

JavaScript在执行它时会对您的函数执行一些特殊操作。

It sets the value of this inside the function body to be myInstance. Additionally, it creates a reference to MyFunction.prototype and stores it as an internal property of myInstance.

它将函数体内的this值设置为myInstance。此外,它还创建了对MyFunction.prototype的引用,并将其存储为myInstance的内部属性。

When your code is executing, the rule that the interpreter follows is such that, if you try to access a property on myInstance that it can't find, it will follow that reference to the function's prototype and look there. This forms a chain, known as the prototype chain that leads all the way up to Object.prototype.

当您的代码执行时,解释器遵循的规则是,如果您尝试访问myInstance上无法找到的属性,它将遵循对该函数原型的引用并查看。这形成了一个链,称为原型链,一直到Object.prototype。

Here's an example:

这是一个例子:

function Dog(name, breed) {
  this.name = name;
  this.breed = breed;

  //if you don't specify a return value, `this` will be returned
}

Dog.prototype.speak = function() {
  alert('Ruff, I\'m ' + this.name + ' the talking ' + this.breed);
}

var myDog = new Dog('buttercup', 'poodle');
myDog.speak();

3 个解决方案

#1

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