Run results for: True object merge comparison

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:69.0) Gecko/20100101 Firefox/69.0

Browser: Firefox 69

Operating system: Linux

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
Using Reduce ES5	3650723.0 Ops/sec
Using Reduce ES5 (test with `in`)	3501851.0 Ops/sec
Using Reduce ES5 (test with `hasOwnProperty`)	3520716.0 Ops/sec
Using Reduce ES6	2175249.0 Ops/sec
Using Reduce ES6 (test with `in`)	2121036.0 Ops/sec
Using Reduce ES6 (test with `hasOwnProperty`)	2144708.0 Ops/sec
Using For...	6637014.0 Ops/sec
Using For... (test with `in`)	6695593.0 Ops/sec
Using For... (test with `hasOwnProperty`)	6725905.0 Ops/sec
Using For... In	17939290.0 Ops/sec
Using For... In (test with `in`)	18357430.0 Ops/sec
Using For... In (test with `hasOwnProperty`)	18217460.0 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`)