Run results for: JavaScript spread operator vs Object.assign performance 2123 123123

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Safari/537.36

Browser: Chrome 76

Operating system: Mac OS X 10.14.6

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
Using the spread operator	1007455.0 Ops/sec
Using Object.assign	397465.2 Ops/sec
Empty object assign	213903.4 Ops/sec

Script Preparation code:

var firstObject = { sampleData: 'Hello world', sampleData2: 'Hello world', sampleData3: 'Hello world',sampleData4: 'Hello world' };
var secondObject = { moreData: 'foo bar',moreData2: 'foo bar',moreData3: 'foo bar',moreData4: 'foo bar' };

var unit = {"name":"New unit gg sfsd  wefwe f ss2223 g","unitType":1,"users":[],"centralCheckLists":[],"unitScheduling":{"dailyActivities":[{"activeDayOfWeek":1,"activeFromHour":"06:00","activeToHour":"22:00","endOfDay":"00:00","activeOffset":false},{"activeDayOfWeek":2,"activeFromHour":"06:00","activeToHour":"22:00","endOfDay":"00:00","activeOffset":false},{"activeDayOfWeek":3,"activeFromHour":"06:00","activeToHour":"22:00","endOfDay":"00:00","activeOffset":false},{"activeDayOfWeek":4,"activeFromHour":"11:00","activeToHour":"22:00","endOfDay":"00:00","activeOffset":false},{"activeDayOfWeek":5,"activeFromHour":"23:00","activeToHour":"22:00","endOfDay":"00:00","activeOffset":false}],"excludedDates":[]},"documentType":6,"revisionId":4,"id":"b99bff7d-9f54-42ea-8b0a-a02827a58d3b","tenantId":"11211c12-455e-4c2f-827b-beb180e33b54","createdByUserId":null,"lastModifiedUserId":null,"isDeleted":false,"_etag":"\"02007ee4-0000-0d00-0000-5d550fdc0000\""};
var data = {name:"New name", unitScheduling:{}};

function generateFields(user, data){
        const baseUnitScheduling = {
            excludedDates: [],
            dailyActivities: ([1, 2, 3, 4, 5]).map(day => ({
                activeDayOfWeek: day,
                activeToHour: '22:00',
                activeFromHour: '06:00',
                activeOffset: false,
            })),
        };

        const unitScheduling = user.unitScheduling || data.unitScheduling || baseUnitScheduling;

        unitScheduling.dailyActivities = unitScheduling.dailyActivities || baseUnitScheduling.dailyActivities;
        unitScheduling.excludedDates = unitScheduling.excludedDates || baseUnitScheduling.excludedDates;

        return {
            unitScheduling,
            users: user.users || data.users || [],
            centralCheckLists: user.centralCheckLists || data.centralCheckLists || [],
        };
    }

Tests:

Using the spread operator
const finalObject ={ ...unit, ...data, ...generateFields(unit, data), }
Using Object.assign
const finalObject = Object.assign(unit, data, generateFields(unit, data));
Empty object assign
const finalObject = Object.assign({}, unit, data, generateFields(unit, data))

Run results for: JavaScript spread operator vs Object.assign performance 2123 123123

Using the spread operator

Using Object.assign

Empty object assign