CODEWITHSUNDEEP
javascriptarraysobject
P.Ellis
P.Ellis

Reputation: 55

Most efficient to search a javascript object or an array of objects

I have an array of JavaScript objects

var arrayObjs = [
{ id:abc123, radius:5.0},
{ id:def235, radius:2.5},...]

I have been using a for loop to find a particular object with id = def235, would it be more efficient to use an object like

var objectObjs = {
{ abc123:{ id:abc123, radius:5.0}},
{ def235:{ id:def235, radius:2.5}},...}

Upvotes: 0

Views: 1905

Answers (2)

Ivan Sivak
Ivan Sivak

Reputation: 7498

Just for fun, I tried it: https://jsperf.com/accessor-test-loop-vs-object

Of course, as T.J. described - access by an object property is much faster. Interestingly, on Chrome the difference is much greater than on Firefox as I just tried out. Try to run the test of Chrome and Firefox or Edge. 

var arrayObjs = [
  { id:'abc123', radius:5.0},
  { id:'def235', radius:2.5}
];

for (var i = 0; i < arrayObjs.length; i++) {
  if (arrayObjs[i].id == 'def235') {
    // found it
    break;
  }
}

..VS..

var objectObjs = {
  abc123:{ id: 'abc123', radius: 5.0},
  def235:{ id: 'def235', radius: 2.5}
}

var found = !!objectObjs.def235;
if (found) {
  // ..
}

Upvotes: 0

T.J. Crowder
T.J. Crowder

Reputation: 1074505

would it be more efficient to use an object like

If you're looking up by id, yes, almost certainly, but your example has an extra layer of {} you'll want to remove:

var objectObjs = {
    abc123:{ id:abc123, radius:5.0},
    def235:{ id:def235, radius:2.5},
    //...
};

JavaScript objects are highly-optimized for property retrieval by name.

Another option is to use a Map, which is also optimized for retrieval by key.

If you use an object, probably best to create it via Object.create(null) so it doesn't inherit Object.prototype properties. You probably aren't going to look up ids like toString or valueOf, but still... :-) So perhaps:

var objectObjs = Object.assign(Object.create(null), {
    abc123:{ id:abc123, radius:5.0},
    def235:{ id:def235, radius:2.5},
    //...
});

It's also trivial to create that object from your array, to avoid typing the ids twice and the opportunity for error that introduces:

var arrayObjs = [
{ id:abc123, radius:5.0},
{ id:def235, radius:2.5},/*...*/];
var objectObjs = Object.create(null);
arrayObjs.forEach(entry => { objectObjs[entry.id] = entry; });

Upvotes: 1

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