How to Push and Replace Value in Array by Object Key

Question

I'm wondering if it's possible to push an object to an array and if the id data-seats already exists replace/overwrite the value on next click.

Code:

var active_filters = [];
$("a").on('click', function() {
    active_filters.push({id: "data-seats", value: increment_value });
});

So far, I have the above with getting the object pushed to the array :) — Michael
– Michael, Commented May 4, 2018 at 14:49
Very nearly a duplicate of stackoverflow.com/questions/28961994/… (and the several others like it). — T.J. Crowder
– T.J. Crowder, Commented May 4, 2018 at 14:52

T.J. Crowder · Accepted Answer · 2018-05-04 15:20:45Z

2

I'm wondering if it's possible to push an object to an array and if the id data-seats already exists replace/overwrite the value on next click.

Yes (see below), but if you're looking for a structure for storing things by a unique key, an array isn't really your best option. An object (created with Object.create(null) so it doesn't inherit any properties) or Map would be a better choice. Then you'd just do

// With an object
active_filters["data-seats"] = (active_filters["data-seats"] || 0) + 1;

or

// With a Map
active_filters.set("data-seats", (active_filters.get("data-seats") || 0) + 1);

Those work because if data-seats isn't on the active_filters object/Map, active_filters["data-seats"]/active_filters.get("data-seats") is undefined, and undefined || 0 is 0. (Then we add 1 to it, and set the new value.)

But you can do it with an array: Use find to see if the object already exists and then update it if it does, or add it if it doesn't:

var obj = active_filters.find(function(entry) { return entry.id === "data-seats"; });
if (obj) {
    ++obj.value;
} else {
   active_filters.push({id: "data-seats", value: 1});
}

edited May 4, 2018 at 15:20

answered May 4, 2018 at 14:57

T.J. Crowder

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2 Comments

Michael Over a year ago

Thanks so much TJ, this is perfect! Quick question...If using the method where I'm first checking if the object exists using find...if the value ever == 0, how can I then remove this object data-seats from array?

T.J. Crowder Over a year ago

@Michael: For that, you wouldn't use find, you'd use findIndex and then splice with the resulting index.

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