Javascript performance and comparing objects vs properties of the object

Question

In javascript is it faster to compare via a property or the entire object that has tons of properties? Below is what I currently have but my object has a ton of properties, and the objects list is quite large. Is it better to create a list from a single property off say id and compare the id of the object? objectids.indexOf(object1.id). Would I see a performance increase?

Comparing Against The Object

objects.indexOf(object1);

function Object() {
  this.id = 1;
  this.name = "test";
}

How do you plan on comparing the entire object? In any case, comparing a unique identifier would be the way to go. — Tyler Roper
– Tyler Roper, Commented Dec 7, 2018 at 20:32
indexOf will compare object references, so you'd need to show how you're populating objects to know if it would even work... — Heretic Monkey
– Heretic Monkey, Commented Dec 7, 2018 at 20:36
jsfiddle.net/qx6wgem0/5 - Admittedly this may not be entirely correct, however from running the tests 10000 times on a dataset of 20000 simple objects, it looks like doing an indexOf by object reference is roughly twice as fast as doing an indexOf by ID. — Tyler Roper
– Tyler Roper, Commented Dec 7, 2018 at 21:03

Jonas Wilms · Accepted Answer · 2018-12-07 20:50:01Z

1

Note that both versions aren't equivalent:

  ({ id: 1}) === ({ id: 1 }) // false      
  ({ id: 1}).id === ({ id: 1 }).id // true

If both cases work the same indexOf has to traverse half the array on average to get the index, it doesn't really matter if that array is an array of ids or objects. To get O(1) lookup time use a Set instead.

answered Dec 7, 2018 at 20:50

Jonas Wilms

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