Getting keyname of parent

Question

I have a function like this:

this.doStuff({
    'testkey': {
        testfunction: function() {
            // will return testfunction
            console.log(Object.keys(this));
        }
    }
});

Is there are a way of getting testkey within the testfunction scope?

The Object.keys(this) will return testfunction.

@AndréDion thanks. that works for my example. but what if the object is a parameter for a function and doesnt have name? — Colin Rauch, Dec 05 '16 at 12:33
Can you update your question with an example that more closely matches your problem? — André Dion, Dec 05 '16 at 12:35
I may be wrong by I have the impression that there's no link for the internal function to the external object that you can use. — Álvaro González, Dec 05 '16 at 12:39
Is your example intended to convey that you are passing an anonymous object (containing `'testKey': {...}`) as an argument to the `this.doStuff()` function? — doppelgreener, Dec 05 '16 at 12:49
yes. that example is exactly what I use. Only the names are different. — Colin Rauch, Dec 05 '16 at 13:08

score 2 · Answer 1 · edited May 23 '17 at 12:24

The JavaScript this keyword is a bit of an unusual beast — it's going to change depending on how a function is called, and most of the time, this will refer to the function it's inside. In this scenario, that's just testfunction, so naturally it's going to give you only the results local to that function.

There's various tutorials on understanding this available:

Here on Stack Overflow: How does the "this" keyword work?
QuirksMode: The this keyword
Mozilla Developer Network: this operator reference

In your scenario, Object.keys() takes an object and returns its keys. If you want the keys of your object, you need to give it that (I've renamed your variables though):

var foo = {
    'key': {
        func: function() {
            console.log(Object.keys(foo)); // <------
        }
    }
};

A.T. · Answer 2 · 2016-12-06T04:54:29.540

2

if you know which method to call inside the javascript object, then you can do so.

You can preserve the scope of caller using apply or call method

function doStuff(ob){
  ob[Object.keys(ob)]['testfunction'].call(ob);
}

doStuff({
    'testkey': {
        testfunction: function() {
            // will return testkey
            console.log(Object.keys(this));
        }
    }
});

edited Dec 06 '16 at 04:54

answered Dec 05 '16 at 12:48

A.T.

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score 1 · Answer 3 · answered Dec 05 '16 at 12:41

you simply can do :

var object = {
    'testkey': {
        testfunction: function() {
            // will return testfunction
            console.log(Object.keys(object));
        }
    }
};

because inside the function scope you can see the global var 'object'

Getting keyname of parent

3 Answers3