MeasureThat.net

Run results for: Initializing array with n undefined items

worth to note that the maximum callstack size is exceeded for the first test case (spread operator) with n = 1 million

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Run details:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0 Safari/605.1.15
Safari 14
Mac OS X 10.15.7
Desktop
4 years ago
Test name Executions per second
[...Array(n).keys()].map(k => undefined) 60.8 Ops/sec
Array.apply(null, { length: 4 }) 0.0 Ops/sec
Array.from 57.5 Ops/sec
Array(n).fill(undefined) 7663.5 Ops/sec
for loop push 45.8 Ops/sec
Script Preparation code:
AخA
 
var n = 100000; // 100k
Tests:

  • [...Array(n).keys()].map(k => undefined)

     
    [...Array(n).keys()].map(k => undefined);

  • Array.apply(null, { length: 4 })

     
     Array.apply(null, { length: n });

  • Array.from

     
    Array.from({ length: n }, () => undefined);

  • Array(n).fill(undefined)

     
    Array(n).fill(undefined)

  • for loop push

     
    const arr = [];
    for (let i = 0; i < n; i++) {
      arr.push(undefined);
    }