What's a clean way to use an object literal to track several (unknown) counts?

Question

Given the following code, there is the variable counts that counts the amount of times the function functionThatGivesSomeKnownOrUnknownStatus gives each status.

const counts = {};

for (let i = 0; i < 100; i++) {
    const status = functionThatGivesSomeKnownOrUnknownStatus();

    counts[status] = counts[status] ? counts[status] + 1 : 1;
}

The part I don't like is this line counts[status] = counts[status] ? counts[status] + 1 : 1;, is there a way to make it shorter and simpler/less redundant/cleaner? This is a node script so ES6/7 solutions are welcome.

One way could be initializing the counts literal with the keys already set to 0, but I don't know the status the function can give.

Tried to make the title as clear and concise as possible, if it can be improved, feel free to edit it.

`counts[status] = (counts[status] || 0) + 1` saves one repetition. — Ry-, Apr 01 '19 at 18:21
A possible approach for more semantic is using a [default dict](https://stackoverflow.com/questions/19127650/defaultdict-equivalent-in-javascript) with value 0: — juvian, Apr 01 '19 at 18:23
(Don’t implement a default dict with proxies like in the top answer to that question, though. It’s much cleaner to do it on top of `Map`.) — Ry-, Apr 01 '19 at 18:25

score 0 · Accepted Answer · answered Jul 29 '19 at 00:37

As @Ry commented, I ended up using this solution:

counts[status] = (counts[status] || 0) + 1;

Inside the code:

const counts = {};

for (let i = 0; i < 100; i++) {
    const status = functionThatGivesSomeKnownOrUnknownStatus();

    counts[status] = (counts[status] || 0) + 1;
}

What's a clean way to use an object literal to track several (unknown) counts?

1 Answers1