Question

I want something like this:

var myObj = {};
myObj["a"]["b"].push({"c":"d"});

I want myObj to become: {"a":{"b":[{"c":"d"}]}} but I get an error

Cannot set property ‘b’ of undefined

Yes, I know I can create it step by step like that:

var myObj={};
myObj["a"]={};
myObj["a"]["b"]=[];
myObj["a"]["b"].push({"c":"d"});

But what if myObj already has some structure and I don’t want to destroy it. E.g:

var myObj={"a":{"e":"f"}};

if I write myObj["a"]={}; I’ll lose data.
Sure I can write

if(myObj["a"]==null){
myObj["a"]={}
}

But it’s too bulky! That would be great if I could just write smth like myObj["a"]["b"].push({"c":"d"}); without checking for null on every step.
Any suggestions how to do this? May be there is a way to override JS native Object or smth like that?
Thank you in advance!

Answer 1

I’m afraid it’s not possible to override JS’s native functionalities like that.

You’re going to have to check for sub-properties.

If you want to make sure a property exists on a object, without overriding it, do something like this:

myObj['a'] = myObj['a'] || {};

This sets myObj['a'] to itself if it has a value, or to a new empty object if it doesn’t.

Then do the same for myObj['a']['b'], and push to that:

myObj['a']['b'] = myObj['a']['b'] || [];
myObj['a']['b'].push({"c":"d"});