Run results for: push-spread or splice performance

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.1.2 Safari/605.1.15

Browser: Safari 14

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
push-spread	15015.3 Ops/sec
splice	14341.6 Ops/sec
new array	100009.1 Ops/sec

Script Preparation code:

var a1 = [];
var a2 = [];
var a3 = [];
var b = [];
var N = 10000;
for (let i = 0; i < N; i++) {
    a1.push(i);
    a2.push(i);
    a3.push(i);
    b.push(N - i);
}

Tests:

push-spread
a1.length = 0; a1.push(...b);
splice
a2.splice(0, a1.length, ...b);
new array
a3 = [...b];

Run results for: push-spread or splice performance

push-spread

splice

new array