Assigning multi dimensional array element in simple way

Question

I want to quickly assign like this:

obj = {};
obj["train-11456"]["2016-12-11" ]["chair car"] = 'waitlisted';

All those elements are objects.

We can do this in PHP and it creates them all automatically.

What is the simplest way to assign like this?

Longer way is:

obj["train-11456"] = {} //only if this key does not already exist
obj["train-11456"]["2016-12-11" ] = {}; //only if this key does not alreadu exist
obj["train-11456"]["2016-12-11" ]["chair car"] = 'waitlisted';

• Software Engineer: You can't do that directly in javascript as arrays (which is what the [] brackets represent) can only have numeric indexes. This is an OO language (ish) so you have to deal with objects.

Answer 1

You can do like this

obj = {
 "train-11456": {
 "2016-12-11": {
 "chair car" : "waitlisted"
 }
 }
};

OR

obj = {"train-11456":{"2016-12-11":{"chair car":"waitlisted"}}};

• Siva: obj["train-11456"]["2016年12月11日" ]["chair car"] The difference i feel is, the curly braces instead of square brackets and closed at the end instead of immediate. The number of curly brackets and square brackets are same if you see.
• user5858: also it discards earlier object data. Of little use.
• Siva: If you already defined obj["train-11456"]["2016年12月11日" ], then you are free to use obj["train-11456"]["2016年12月11日" ]["chair car"] = 'waitlisted'; without any issues

Answer 2

Well there is no straight way to do this. But you can write a utility function to do it for you. Its kind of shorthand

function objUtil (obj) {
 var _o = obj || {};
 return function () {
 var args = [].slice.call(arguments, 0),
 val = args.splice(args.length - 1, 1)[0],
 res = {},
 index, length, key, objPointer, lastObjPtr;
 objPointer = _o;
 for (index = 0, length = args.length; index < length; index ++) {
 key = args[index];
 lastObjPtr = objPointer;
 objPointer = objPointer[key] = {};
 }
 lastObjPtr[key] = val;
 return _o;
 }
}

And then call it like

var obj,
 populateObj = objUtil(obj={});
populateObj('train-11456', '2016-12-11', 'chair car', 'waitlisted');
console.log(obj);