Creating a JavaScript object with 3 methods throws Object has no method

Question

i'm trying to create a JavaScript object named human with three methods walk, eat and talk, and i want to call it like this (no method should print any values): human.talk('hello').walk('home').eat('pizza').

I have this code:

var human = {
    talk : function talk(t){

    },
    walk : function walk(w){

    },
    eat : function eat(e){

    }
};

console.log(human.talk('hello').walk('home').eat('pizza'));

But i'm receiving Uncaught TypeError: Cannot call method 'walk' of undefined

Why??

Does talk return the human? It has to for chaining to work. — Bergi
– Bergi, Commented Oct 8, 2013 at 0:59

Robin · Accepted Answer · 2013-10-08 00:31:06Z

6

Each function needs to return this if you want to be able to chain functions. You are getting the error because the function talk is returning undefined and you are essentially trying to call undefined.walk('home').

answered Oct 8, 2013 at 0:31

Robin

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Comments

Thilo · Accepted Answer · 2013-10-08 00:30:54Z

0

You cannot just chain calls like that. Did you mean to log all three results?

console.log(human.talk('hello'),human.walk('home'),human.eat('pizza'));

If you did want to have a "fluent" call chain, your functions all need to return this (so that you can proceed to call functions on it).

answered Oct 8, 2013 at 0:30

Thilo

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Comments

kamikazeOvrld · Accepted Answer · 2013-10-08 01:09:15Z

its not exactly clear what you are trying to achieve with the code above but from what I can see, there are two options:

A. you are trying to call all three functions and have console.log print the results of the functions in sequence, one after the other, ie you are using the (.) operate to concatenate the results of the function calls into one long string, in this case i would like to remind you that the concatenation operator in javascript, unlike, say php is + and not (.) so rather use this:

console.log(human.talk('hello') + walk('home') + eat('pizza'));

B. You actually want to call a chain for function calls. in which case i would like to remaind you that the . operator retrieves a property or method of an object ie the syntax is (object).(property), always the identifier or value before the operator should be an object. So, in order for you chain call to work, all your given function should return an object,(well, maybe except for the last one) in this case, the appropriate return value would be "this":

var human = {
    talk : function(t){
       return this;

    },
    walk : function(w){
       return this;
    },
    eat : function(e){
       return this;//or whatever here
    }
};

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