当使用function.apply（this，arguments）时，参数的顺序会混合

Question

So I was trying to 'inherit' parameters in someway and I came across the use of

function.apply(this, arguments)

And it did the job... well for the most part. What I am getting is that when I'm calling a function from the parent object the arguments of the parent function get in front of the others and when I call a function from the inheritor they don't.

Here's my code:

function Human(name, gender, tel, address){
    this.name = name;
    this.gender = gender;
    this.address = address;
    this.tel = tel;
}

Human.prototype.introduce = function(){
    console.log("Hi I'm " + this.name + " a " + this.gender + " from " + this.address + 
    ". My number is " + this.tel);
}

    Student.prototype = new Human; 
    Student.prototype.constructor = Student;


function Student(school,marks){
    Human.apply(this, arguments);
    this.school = school;
    this.marks = marks;

}

Student.prototype.average = function(){
    this.total = 0;
    this.average = 0;
    this.markslength = this.marks.length;
    for(var i = 0; i<this.markslength; i++){
        this.total = this.total + this.marks[i]
    }
    this.average = (this.total)/(this.markslength);

    var marks3 = [6,6,2]
    var Nasko = new Student('Nasko', 'Male', 14421687, 'Sofia', 'FELS', marks3);

And when I do: console.log(Nasko.name); It's OK. But when I do console.log(Nasko.average()); It gives me NaN. So my question is - how to actually 'fix' it

Sorry if I asked an already asked question but I couldn't really think of how to ask it in any short a redirection to another similar post will be welcome. Thanks in advance.

Answer 1

You are using first two arguments for school and marks which actually name and gender.

You can use arguments for reading last values

function Student(){
    Human.apply(this, arguments);
     var len = arguments.length;
    this.school = arguments[arguments.length-2]; // second last argument is school
    this.marks =  arguments[arguments.length-1]; // last argument is mark.

}

Answer 2

The value of two parameters named "school" and "marks" in the "Student" constructor will be "Nasko" and "Male" and in the "Human" class you are passing "Nasko" as "name" and "Male" as "gender" . I think you are confused with the apply and passing arguments to it a little bit. Of course after initializing the code marks is a string value of "Male" and you cannot have the average result.

Hope it helps.

Cheers