通过原型添加方法

Question

I am trying to add a height method but now when i call it without the () . How can i use this it as a method the benji.height() method?I mean with the Parenthesis at the end?

function Dog() {
    this.tail = true;
    this.height = 33;

}
 var benji = new Dog();
 var rusty = new Dog();

 Dog.prototype.height = function() {
     return "the height is " +  this.height + " cms";
 };

console.log(benji.height);

Answer 1

You have a field named height and you are trying to add a method called height .
You need to give it an unambigious name and it will work.

 function Dog() { this.tail = true; this.height = 33; } var benji = new Dog(); var rusty = new Dog(); Dog.prototype.getHeight = function() { return "the height is " + this.height + " cms"; }; document.body.innerHTML = "<b>height:</b> " + (benji.height) + "<br/>"; document.body.innerHTML += "<b>getHeight():</b> " + benji.getHeight(); 

Answer 2

So you have height variable in both the place Object and object prototype. So according to prototype chain it will first lookup in Object and then its prototype.

Here

function Dog() {
    this.tail = true;
    this.height = 33;

}

height variable will store in object So it will find height which is not a function that a reason you are not able to call as benji.height();

So as other user suggest just change the name of function you can call it as you want.