JavaScript新对象可以将原型链接到另一个对象

Question

I have 3 questions about the following code that I have found in a text book about JavaScript called "JavaScript: The Good Parts".

It says that when we make a new object, we can select the object that should be its prototype.

Part 1: lets say we have the following object

var person = {
    first_name: "Tim",
    last_name: "Thompson",
    middel_name: "Jack",
    nick_name: "GoldTeeth",
    age:30
  };

Part 2: then we are going to add the Create function to Object using following code

Object.create = function(o){
    var F = function(){};
        F.prototype = o;
        return new F(); 
}

and then later we can map any new object's prototype to "person" using Object.create() function

part 3: example//

  var another_person = Object.create(person);
  alert(another_person.first_name); //Tim

1. why in the body of create function why we assign F to a function
2. and at the end return a new F()
3. why in part 3 we assign another_person to a function

I understand that in JavaScript functions are object but I can't follow the logic. Could anyone help me?

Answer 1

When you have a code like this:

var foo = bar;

then your variable called foo will get the value bar . So it is bar assigned to foo , not foo assigned to bar , therefore you have some misconceptions in your question.

As about the code posted. The first part creates an object and assigns it to person . The second part assigns a function to Object.create . The function creates a new empty function and assigns it to F . When this is done, the parameter called o is assigned to F 's prototype . Since F has a prototype , it can be instantiated and a new instance of F is returned. The third part is a test code. It takes person and using Object.create instantiates a new person .