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Run results for: Array.prototype.concat vs spread operator - Immutable version

Compare the new ES6 spread operator with the traditional concat() method. All methods create a fresh array to simulate an environment where immutable data is a requirement.

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Run details:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36
Chrome 65
Windows
Other
6 years ago
Test name Executions per second
Array.prototype.concat 41337.9 Ops/sec
spread operator 294.6 Ops/sec
Lodash merge 1451.4 Ops/sec
HTML Preparation code:
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<script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js'></script>
Script Preparation code:
 
var array1 = (new Array(10000)).fill(Math.random(), 0, 9999);
var array2 = (new Array(10000)).fill(Math.random(), 0, 9999);
Tests:

  • Array.prototype.concat

     
    var other = array1.concat(array2);

  • spread operator

     
    var other = [ ...array1, ...array2 ]

  • Lodash merge

     
    var other = _.merge([], array1, array2);