Javascript: how do I access a key in a dynamically-named nested object?

Question

Here's my situation: I'm working with an array that has a bunch of nested objects. One of those nested objects has a name that changes dynamically. How can I consistently access a key of one of it's child objects?

Here's a few examples of the paths that it can have:

kml[id].overlayData._layers.136._bounds._northEast.lat
kml[id].overlayData._layers.143._bounds._northEast.lat
kml[id].overlayData._layers.82._bounds._northEast.lat
kml[id].overlayData._layers.87._bounds._northEast.lat
kml[id].overlayData._layers.76._bounds._northEast.lat

The child object that I'm trying to access is 'lat', which has a couple of keys within it.

Apologies for any weird / incorrect use of terminology, I'm still trying to get my head around concepts like this.

Do you know what the number of the object you want to access is? Where is that stored? — Feathercrown
– Feathercrown, Commented Oct 26, 2016 at 17:17
@Feathercrown I've edited the question to try and clarify a bit more . — Rich
– Rich, Commented Oct 26, 2016 at 17:20

Nina Scholz · Accepted Answer · 2016-10-26 17:34:25Z

1

You could get the key with Object.keys.

var keys = Object.keys(kml[id].overlayData._layers);

// access
keys.forEach(function (key) {
    // kml[id].overlayData._layers[key]._bounds._northEast.lat
});

For only one unknown key, you could use directly the first element of the keys array

var key = Object.keys(kml[id].overlayData._layers)[0];

// access with
kml[id].overlayData._layers[key]._bounds._northEast.lat

edited Oct 26, 2016 at 17:34

answered Oct 26, 2016 at 17:20

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Feathercrown Over a year ago

This only gets the first key; additionally, it can be a different key every time!

Nina Scholz Over a year ago

i do not understand you. the question was, how to access a property without knowing the name. in your answer, you know the name, but that is not the question, as i read it. please add a less complicated solution.

Feathercrown Over a year ago

Our answers are both correct and flawed for different interpretations of the question.

Rich Over a year ago

Thanks @NinaScholz, you gave the best answer to my admittedly poorly worded question! However, am I right in thinking that Object.keys won't return keys that have been marked as 'enumerable: false'?

Feathercrown · Accepted Answer · 2016-10-26 17:21:08Z

0

Try this, if I understand the question correctly:

var number = 354; //whatever number you want to get the value from
kml[id].overlayData._layers['number']._bounds._northEast.lat

Note that you can't use blahblah.123 to access a number-started property; use blahblah['123'] instead. This also allows you to pass in variables, like the example above.

answered Oct 26, 2016 at 17:21

Feathercrown

2,5911 gold badge19 silver badges32 bronze badges

Comments

kevin ternet · Accepted Answer · 2016-10-26 17:41:17Z

0

You can loop thanks to for..in loop

for (var prop in kml[id].overlayData._layers) 
   console.log(kml[id].overlayData._layers[prop]._bounds._northEast.lat);

answered Oct 26, 2016 at 17:41

kevin ternet

4,6322 gold badges21 silver badges27 bronze badges

Collectives™ on Stack Overflow

Javascript: how do I access a key in a dynamically-named nested object?

3 Answers 3

4 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

4 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related