Run results for: True object merge comparison

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.27 Safari/537.36 OPR/62.0.3331.2 (Edition developer)

Browser: Opera 62

Operating system: Linux

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
Using Reduce ES5	3307647.8 Ops/sec
Using Reduce ES5 (test with `in`)	3006600.0 Ops/sec
Using Reduce ES5 (test with `hasOwnProperty`)	3157945.8 Ops/sec
Using Reduce ES6	1640787.5 Ops/sec
Using Reduce ES6 (test with `in`)	1538364.4 Ops/sec
Using Reduce ES6 (test with `hasOwnProperty`)	1594372.1 Ops/sec
Using For...	4654527.0 Ops/sec
Using For... (test with `in`)	4651907.5 Ops/sec
Using For... (test with `hasOwnProperty`)	5064922.0 Ops/sec
Using For... In	20705678.0 Ops/sec
Using For... In (test with `in`)	18856086.0 Ops/sec
Using For... In (test with `hasOwnProperty`)	27150900.0 Ops/sec

Tests:

Using Reduce ES5
const firstObject = { a: 'Hello,', b: 'World' }; const secondObject = { b: 'World!', c: '!' }; const mergedObject = Object.keys(firstObject) .reduce(function(accumulator, key) { let toMerge = secondObject[key]; if (!toMerge) { toMerge = firstObject[key]; } accumulator[key] = toMerge; return accumulator; }, {});
Using Reduce ES5 (test with `in`)
const firstObject = { a: 'Hello,', b: 'World' }; const secondObject = { b: 'World!', c: '!' }; const mergedObject = Object.keys(firstObject) .reduce(function(accumulator, key) { accumulator[key] = firstObject[key]; if (key in secondObject) { accumulator[key] = secondObject[key]; } return accumulator; }, {});
Using Reduce ES5 (test with `hasOwnProperty`)
const firstObject = { a: 'Hello,', b: 'World' }; const secondObject = { b: 'World!', c: '!' }; const mergedObject = Object.keys(firstObject) .reduce(function(accumulator, key) { accumulator[key] = firstObject[key]; if (secondObject.hasOwnProperty(key)) { accumulator[key] = secondObject[key]; } return accumulator; }, {});
Using Reduce ES6
const firstObject = { a: 'Hello,', b: 'World' }; const secondObject = { b: 'World!', c: '!' }; const mergedObject = Object.keys(firstObject) .reduce((a, key) => { let toMerge = secondObject[key]; if (!toMerge) { toMerge = firstObject[key]; } return { ...a, [key]: toMerge}; }, {});
Using Reduce ES6 (test with `in`)
const firstObject = { a: 'Hello,', b: 'World' }; const secondObject = { b: 'World!', c: '!' }; const mergedObject = Object.keys(firstObject) .reduce((a, key) => { let toMerge = firstObject[key]; if (key in secondObject) { toMerge = secondObject[key]; } return { ...a, [key]: toMerge}; }, {});
Using Reduce ES6 (test with `hasOwnProperty`)
const firstObject = { a: 'Hello,', b: 'World' }; const secondObject = { b: 'World!', c: '!' }; const mergedObject = Object.keys(firstObject) .reduce((a, key) => { let toMerge = firstObject[key]; if (secondObject.hasOwnProperty(key)) { toMerge = secondObject[key]; } return { ...a, [key]: toMerge}; }, {});
Using For...
const firstObject = { a: 'Hello,', b: 'World' }; const secondObject = { b: 'World!', c: '!' }; let mergedObject = firstObject; const keys = Object.keys(mergedObject); for (let index = 0; index < keys.length; index++) { const key = keys[index]; if (secondObject[key]) { mergedObject[key] = secondObject[key]; } }
Using For... (test with `in`)
const firstObject = { a: 'Hello,', b: 'World' }; const secondObject = { b: 'World!', c: '!' }; let mergedObject = firstObject; const keys = Object.keys(mergedObject); for (let index = 0; index < keys.length; index++) { const key = keys[index]; if (key in secondObject) { mergedObject[key] = secondObject[key]; } }
Using For... (test with `hasOwnProperty`)
const firstObject = { a: 'Hello,', b: 'World' }; const secondObject = { b: 'World!', c: '!' }; let mergedObject = firstObject; const keys = Object.keys(mergedObject); for (let index = 0; index < keys.length; index++) { const key = keys[index]; if (secondObject.hasOwnProperty(key)) { mergedObject[key] = secondObject[key]; } }
Using For... In
const firstObject = { a: 'Hello,', b: 'World' }; const secondObject = { b: 'World!', c: '!' }; let mergedObject = firstObject; for (let key in mergedObject) { if (secondObject[key]) { mergedObject[key] = secondObject[key]; } }
Using For... In (test with `in`)
const firstObject = { a: 'Hello,', b: 'World' }; const secondObject = { b: 'World!', c: '!' }; let mergedObject = firstObject; for (let key in mergedObject) { if (key in secondObject) { mergedObject[key] = secondObject[key]; } }
Using For... In (test with `hasOwnProperty`)
const firstObject = { a: 'Hello,', b: 'World' }; const secondObject = { b: 'World!', c: '!' }; let mergedObject = firstObject; for (let key in mergedObject) { if (secondObject.hasOwnProperty(key)) { mergedObject[key] = secondObject[key]; } }

Run results for: True object merge comparison

Using Reduce ES5

Using Reduce ES5 (test with `in`)

Using Reduce ES5 (test with `hasOwnProperty`)

Using Reduce ES6

Using Reduce ES6 (test with `in`)

Using Reduce ES6 (test with `hasOwnProperty`)

Using For...

Using For... (test with `in`)

Using For... (test with `hasOwnProperty`)

Using For... In

Using For... In (test with `in`)

Using For... In (test with `hasOwnProperty`)