How to change scope of JavaScript getter?

Question

Given the following object:

var myObj = {
    fname: 'John',
    lname: 'Doe',
    values: {
        get fullName() {
            return this.fname + ' ' + this.lname
        }
    }
};

When trying to access myObj.values.fullName, undefined undefined is returned because the context of this is set to myObj.values, not myObj.

Is there a way to change that? I tried every combination of bind I can think of, but most of the time this just results in syntax error because fullName isn't a regular function.

Can't you use it like `return myObj.fname + ' ' + myObj.lname` ? — Rajaprabhu Aravindasamy, Apr 30 '16 at 15:32

score 1 · Answer 1 · edited May 23 '17 at 12:16

1

You cannot access parent objects in Javascript. Do you need to nest the getter within the values element? The following would work just fine:

var myObj = {
    fname: 'John',
    lname: 'Doe',
    get fullName() {
        return this.fname + ' ' + this.lname
    }
};

alert(myObj.fullName)

edited May 23 '17 at 12:16

Community

1
1

answered Apr 30 '16 at 15:31

BlueRaven

31
3

score 1 · Accepted Answer · answered Apr 30 '16 at 15:32

1

You can access to parent object properties only by myObj.fname and myObj.lname.

var myObj = {
    fname: 'John',
    lname: 'Doe',
    values: {
        get fullName() {
            return myObj.fname + ' ' + myObj.lname
        }
    }
};

answered Apr 30 '16 at 15:32

Ali Mamedov

5,116
3
33
47

felipecamposclarke · Answer 3 · 2016-04-30T15:45:33.237

1

Replace "this" with the name of the object

OPTION 1:

var myObj = {
    fname: 'John',
    lname: 'Doe',
    values: {
        get fullName() {
            return myObj.fname + ' ' + myObj.lname
        }
    }
};

Another alternative:

OPTION 2:

var myObj = {
    fname: 'John',
    lname: 'Doe',
    values: {
        get fullName() {
            return this.parent.fname + ' ' + this.parent.lname
        }
    },
    init: function(){
        this.values.parent = this;
        delete this.init; 
        return this;
    }
}.init()

edited Apr 30 '16 at 15:45

answered Apr 30 '16 at 15:34

felipecamposclarke

934
8
14

Would this work if there are multiple instances of the `myObj` object? – evolutionxbox Apr 30 '16 at 15:45
It is a good point. It works out with the second option (edited in original post) – felipecamposclarke Apr 30 '16 at 15:47
@evolutionxbox, Will my answer was satisfactory for you? – felipecamposclarke Apr 30 '16 at 16:55
1

I think so. It's very similar to the revealing module pattern. – evolutionxbox Apr 30 '16 at 16:57

How to change scope of JavaScript getter?

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