MeasureThat.net

Run results for: Preinitialized array size vs Push operations to an empty one.

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Run details:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.54 Safari/537.36
Chrome 95
Mac OS X 10.15.7
Desktop
3 years ago
Test name Executions per second
Preinitialized size - large difference 4499.9 Ops/sec
Push 7527.0 Ops/sec
Preinitialized size - small difference 8231.4 Ops/sec
Preinitilized size - no difference 8265.1 Ops/sec
Tests:

  • Preinitialized size - large difference

    AخA
     
    let arr = new Array(100000)
    for (var i=0; i<1000; i++) {
      arr[i] = Math.random;
    }
    arr = arr.slice(0, 1000)

  • Push

     
    let arr =[]
    for (var i=0; i<1000; i++) {
      arr.push(Math.random);
    }

  • Preinitialized size - small difference

     
    let arr = new Array(1200)
    for (var i=0; i<1000; i++) {
      arr[i] = Math.random;
    }
    arr = arr.slice(0, 1000)

  • Preinitilized size - no difference

    ​x
     
    let arr = new Array(1000)
    for (var i=0; i<1000; i++) {
      arr[i] = Math.random;
    }
    ​