Question

I am dynamically building an array of objects using a process that boils down to something like this:

//Objects  Array
var objects = [];

//Object Structure
var object1 =  {"id":"foobar_1", "metrics":90};
var object2 = {"id":"some other foobar",  "metrics":50};
objects[0] = object1;
objects[1] = object2;

(Let it be said for the record, that if you can think of a better way to dynamically nest data such that I can access it with objects[i].id I am also all ears!)

There’s ultimately going to be more logic at play than what’s above, but it’s just not written yet. Suffice it to say that the “object1” and “object2” parts will actually be in an iterator.

Inside that iterator, I want to check for the presence of an ID before adding another object to the array. If, for example, I already have an object with the ID "foobar_1", instead of pushing a new member to the array, I simply want to increment its "metrics" value.

If I wasn’t dealing with an array of objects, I could use inArray to look for “foobar_1” (a jQuery utility). But that won’t look into the object’s values. The way I see it, I have two options:

1. Keep a separate simple array of just the IDs. So instead of only relying on the objects array, I simply check inArray (or plain JS equivalent) for a simple “objectIDs” array that is used only for this purpose.

2. Iterate through my existing data object and compare my "foobar_1" needle to each objects[i].id haystack

I feel that #1 is certainly more efficient, but I can’t help wondering if I’m missing a function that would do the job for me. A #3, 4, or 5 option that I’ve missed! CPU consumption is somewhat important, but I’m also interested in functions that make the code less verbose whether they’re more cycle-efficient or not.

Answer 1

I’d suggest switching to an object instead of an array:

var objects = {};
objects["foobar_1"] = {metrics: 90};
objects["some other foobar"] = {metrics: 50};

Then, to add a new object uniquely, you would do this:

function addObject(id, metricsNum) {
    if (!(id in objects)) {
        objects[id] = {metrics: metricsNum};
    } 
}

To iterate all the objects, you would do this:

for (var id in objects) {
    // process objects[id]
}

This gives you very efficient lookup for whether a given id is already in your list or not. The only thing it doesn’t give you that the array gave you before is a specific order of objects because the keys of an object don’t have any specific order.