Run results for: JavaScript shallow copy spread operator vs Object.assign performance 2X

Test name	Executions per second
✓ Using the spread operator	861,337 Ops/sec
Using Object.assign	473,020 Ops/sec

Script Preparation code:

window.objectToCopy = { 
  sampleString1: 'Hello world',
  sampleNumber1: 123456789,
  sampleArray1: ['hello', 'world', 'how', 'are', 'you'],
  sampleString2: 'Hello world',
  sampleNumber2: 123456789,
  sampleArray2: ['hello', 'world', 'how', 'are', 'you'],
  sampleString3: 'Hello world',
  sampleNumber3: 123456789,
  sampleArray3: ['hello', 'world', 'how', 'are', 'you'],
  sampleString4: 'Hello world',
  sampleNumber4: 123456789,
  sampleArray4: ['hello', 'world', 'how', 'are', 'you'],
  sampleString5: 'Hello world',
  sampleNumber5: 123456789,
  sampleArray5: ['hello', 'world', 'how', 'are', 'you'],
  sampleString6: 'Hello world',
  sampleNumber6: 123456789,
  sampleArray6: ['hello', 'world', 'how', 'are', 'you'],
  sampleString7: 'Hello world',
  sampleNumber7: 123456789,
  sampleArray7: ['hello', 'world', 'how', 'are', 'you'],
  sampleString8: 'Hello world',
  sampleNumber8: 123456789,
  sampleArray8: ['hello', 'world', 'how', 'are', 'you'],
  sampleString9: 'Hello world',
  sampleNumber9: 123456789,
  sampleArray9: ['hello', 'world', 'how', 'are', 'you'],
  sampleString10: 'Hello world',
  sampleNumber10: 123456789,
  sampleArray10: ['hello', 'world', 'how', 'are', 'you'],  
}
window.objectToCopy2 = { 
  xsampleString1: 'Hello world',
  xsampleNumber1: 123456789,
  xsampleArray1: ['hello', 'world', 'how', 'are', 'you'],
  xsampleString2: 'Hello world',
  xsampleNumber2: 123456789,
  xsampleArray2: ['hello', 'world', 'how', 'are', 'you'],
  xsampleString3: 'Hello world',
  xsampleNumber3: 123456789,
  xsampleArray3: ['hello', 'world', 'how', 'are', 'you'],
  xsampleString4: 'Hello world',
  xsampleNumber4: 123456789,
  xsampleArray4: ['hello', 'world', 'how', 'are', 'you'],
  xsampleString5: 'Hello world',
  xsampleNumber5: 123456789,
  xsampleArray5: ['hello', 'world', 'how', 'are', 'you'],
  xsampleString6: 'Hello world',
  xsampleNumber6: 123456789,
  xsampleArray6: ['hello', 'world', 'how', 'are', 'you'],
  xsampleString7: 'Hello world',
  xsampleNumber7: 123456789,
  xsampleArray7: ['hello', 'world', 'how', 'are', 'you'],
  xsampleString8: 'Hello world',
  xsampleNumber8: 123456789,
  xsampleArray8: ['hello', 'world', 'how', 'are', 'you'],
  xsampleString9: 'Hello world',
  xsampleNumber9: 123456789,
  xsampleArray9: ['hello', 'world', 'how', 'are', 'you'],
  xsampleString10: 'Hello world',
  xsampleNumber10: 123456789,
  xsampleArray10: ['hello', 'world', 'how', 'are', 'you'],  
}

Run results for: JavaScript shallow copy spread operator vs Object.assign performance 2X

Using the spread operator

Using Object.assign