Run results for: cost of adding new properties to object after creation.

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:138.0) Gecko/20100101 Firefox/138.0

Browser: Firefox 138

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Benchmark engine: Benchmark.js

object literal

730.1M/s

adding properties

21.1M/s

View exact numbers

Test name	Executions per second
✓ object literal	730,089,856 Ops/sec
adding properties	21,080,048 Ops/sec

Script Preparation code:

function objLiteral() {
  
	const obj = {
      _chanPutMsg_m: undefined,
      _doneVal_m: 3213,
      _name: true,
      _args: false,
      _state: "RUNNING",
      _doneCh: undefined,
      _childS: undefined,
      _sleepTimeout_m: undefined,
      _onCancel_m: undefined,
      _cancelCh: undefined,
  	} 
    
    return obj
}

function addProps() {
  
  const obj2 = {}
  
  obj2._chanPutMsg_m = undefined
  obj2._doneVal_m = 3213
  obj2._name = true
  obj2._args = false
  obj2._state = "RUNNING"
  obj2._doneCh = undefined
  obj2._childS = undefined
  obj2._sleepTimeout_m = undefined
  obj2._onCancel_m = undefined
  obj2._cancelCh = undefined
  
  return obj2
}

Tests:

object literal
objLiteral()
adding properties
addProps()