Run results for: [{key, fn}, ...] vs {[key]: fn, ...}

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36

Browser: Chrome 53

Operating system: Mac OS X 10.10.5

Device Platform: Other

Date tested: 8 years ago

Test name	Executions per second
Array	2755.4 Ops/sec
Object	2910.7 Ops/sec

Script Preparation code:

var data = {};
var array = [];
var object = {};
for (var i = 0; i < 1000; i++) {
  var key = Math.random().toString(16).slice(2, 10);
  var fn = function(k) {return data[k];}
  data[key] = Math.random();
  array.push({
    key: key,
    fn: fn
  });
  object[key] = fn;
}

Tests:

Array
var sum = 0; for (var i = 0; i < array.length; i++) { var item = array[i]; sum += item.fn(item.key); }
Object
var sum = 0; var keys = Object.keys(object); for (var i = 0; i < keys.length; i++) { var key = keys[i]; sum += object[key](key); }

Run results for: [{key, fn}, ...] vs {[key]: fn, ...}

Iterating over array of {key, fn} vs object of {[key]: fn}

Array

Object