Benchmark: JavaScript spread operator vs Object.assign performance, large objects

Tests:

Using the spread operator
const firstObject = {} const secondObject = {} for(let i = 1; i < 1000; i++) firstObject[i] = Math.random(); for(let i = 1; i < 1000; i++) secondObject[i] = firstObject[i]; let rnd = Math.floor(Math.random() * 1000); secondObject[rnd] = Math.random(); const finalObject = { ...firstObject, ...secondObject }; console.log("first", firstObject) console.log("second", secondObject) console.log("final", finalObject)
Using Object.assign
const firstObject = {} const secondObject = {} for(let i = 1; i < 1000; i++) firstObject[i] = Math.random(); for(let i = 1; i < 1000; i++) secondObject[i] = firstObject[i]; let rnd = Math.floor(Math.random() * 1000); secondObject[rnd] = Math.random(); const finalObject = Object.assign(firstObject, secondObject); console.log("first", firstObject) console.log("second", secondObject) console.log("final", finalObject)
Using Object.assign (known change)
const firstObject = {} const secondObject = {} for(let i = 1; i < 1000; i++) firstObject[i] = Math.random(); for(let i = 1; i < 1000; i++) secondObject[i] = firstObject[i]; let rnd = Math.floor(Math.random() * 1000); secondObject[rnd] = Math.random(); let diff = {} diff[rnd] = secondObject[rnd]; const finalObject = Object.assign(firstObject, diff); console.log("first", firstObject) console.log("second", secondObject) console.log("final", finalObject)
Using the spread operator (known change)
const firstObject = {} const secondObject = {} for(let i = 1; i < 1000; i++) firstObject[i] = Math.random(); for(let i = 1; i < 1000; i++) secondObject[i] = firstObject[i]; let rnd = Math.floor(Math.random() * 1000); secondObject[rnd] = Math.random(); let diff = {} diff[rnd] = secondObject[rnd]; const finalObject = { ...firstObject, ...diff }; console.log("first", firstObject) console.log("second", secondObject) console.log("final", finalObject)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign
Using Object.assign (known change)
Using the spread operator (known change)

Fastest: N/A

Slowest: N/A

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Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36

Browser/OS: Chrome 126 on Linux

View result in a separate tab

Test name	Executions per second
Using the spread operator	2243.0 Ops/sec
Using Object.assign	3514.5 Ops/sec
Using Object.assign (known change)	7689.6 Ops/sec
Using the spread operator (known change)	7257.2 Ops/sec

JavaScript spread operator vs Object.assign performance, large objects (version: 0)

For large objects, 1 value change only

Comparing performance of: Using the spread operator vs Using Object.assign vs Using Object.assign (known change) vs Using the spread operator (known change)

Created: one month ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

Using Object.assign (known change)

Using the spread operator (known change)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A