MeasureThat.net

Run results for: Reduce and Spread vs. Foreach and Mutate

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Run details:
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:82.0) Gecko/20100101 Firefox/82.0
Firefox 82
Windows
Desktop
4 years ago
Test name Executions per second
Reduce and Spread 2853.5 Ops/sec
ForEach and Mutate (for .. in loop) 841.7 Ops/sec
Mutate with Object.assign 6431.6 Ops/sec
Foreach and Mutate (Object.assign) 7482.4 Ops/sec
Script Preparation code:
AخA
 
var objectsArray = Array(1000).fill(() => {
  const key = Math.random().toString(36).substring(2, 5);
  const value = Math.random().toString(36).substring(2, 5);
  return {[key]: value};
});
Tests:

  • Reduce and Spread

     
    var combined = objectsArray.reduce((memo, obj) => ({...memo, ...obj}), {});

  • ForEach and Mutate (for .. in loop)

     
    var combined = {}
    objectsArray.forEach(obj => {
      for (key in obj) {
        combined[key] = obj[key];
      }
    });

  • Mutate with Object.assign

     
    var combined = Object.assign(...objectsArray)

  • Foreach and Mutate (Object.assign)

     
    var combined = {}
    objectsArray.forEach(obj => Object.assign(combined, obj));