Run results for: 2D array copy | slice vs spread operator vs loop

Test name	Executions per second
✓ Array.prototype.slice	90,581 Ops/sec
spread operator	75,011 Ops/sec
placement loop	48,864 Ops/sec
simple loop	47,338 Ops/sec
pre-built array loop	47,111 Ops/sec

Array.prototype.slice

let param = new Array(50);
for (let a = 0; a < 50; a++) {
    param[a] = new Array(50);
    for (let b = 0; b < 50; b++) {
        param[a][b] = b;
    }
}

let ans = [];
for (let i = 0; i < param.length; i++) {
  ans.push(param[i].slice());
}

spread operator

let param = new Array(50);
for (let a = 0; a < 50; a++) {
    param[a] = new Array(50);
    for (let b = 0; b < 50; b++) {
        param[a][b] = b;
    }
}

let ans = [];
for (let i = 0; i < 50; i++) {
  ans.push([...param[i]]);
}

simple loop

let param = new Array(50);
for (let a = 0; a < 50; a++) {
    param[a] = new Array(50);
    for (let b = 0; b < 50; b++) {
        param[a][b] = b;
    }
}

let ans = [];
for (let i = 0; i < 50; i++) {
  ans.push([]);
  for(let j = 0; j < 50; j++) {
    ans[i].push(param[i][j]);
  }
}

placement loop

let param = new Array(50);
for (let a = 0; a < 50; a++) {
    param[a] = new Array(50);
    for (let b = 0; b < 50; b++) {
        param[a][b] = b;
    }
}

let ans = [];
for (let i = 0; i < 50; i++) {
  ans.push([]);
  for(let j = 0; j < 50; j++) {
    ans[i][j] = param[i][j];
  }
}

pre-built array loop

let param = new Array(50);
for (let a = 0; a < 50; a++) {
    param[a] = new Array(50);
    for (let b = 0; b < 50; b++) {
        param[a][b] = b;
    }
}

let ans = new Array(50);
for (let i = 0; i < 50; i++) {
  ans[i] = new Array(50);
  for(let j = 0; j < 50; j++) {
    ans[i][j] = param[i][j];
  }
}

Run results for: 2D array copy | slice vs spread operator vs loop

Compare 2D array copy with the spread operator vs slice vs loop

Array.prototype.slice

spread operator

simple loop

placement loop

pre-built array loop