Primitive array benchmark

gistfile1.js

let arr;
let foo = {};

// Category A: Pre-determined array size with index assignment
console.log("Pre-determined array size with index assignment");
console.log("%cSize | Time (ms)", "font-weight: bold");
for (let x of [1000, 1001, 10000, 10001, 100000, 100001, 10_000_000, 10_000_001]) {
  const iterations = 10; // number of times to run the test
  const start = performance.now();
  for (let i = 0; i < iterations; i++) {
    arr = Array(x);
    for (let j = 0; j < x; j++) {
      arr[j] = Object.assign({}, foo);
    }
  }
  const end = performance.now();
  console.log(`%c${x} | ${(end - start) / iterations}`, "color: blue");
}

// Category B: Non-determined array size with index assignment
console.log("\nNon-determined array size with index assignment");
console.log("%cSize | Time (ms)", "font-weight: bold");
for (let x of [1000, 1001, 10000, 10001, 100000, 100001, 10_000_000, 10_000_001]) {
  const iterations = 10; // number of times to run the test
  const start = performance.now();
  for (let i = 0; i < iterations; i++) {
    arr = [];
    for (let j = 0; j < x; j++) {
      arr[j] = Object.assign({}, foo);
    }
  }
  const end = performance.now();
  console.log(`%c${x} | ${(end - start) / iterations}`, "color: green");
}

// Category C: Non-determined array size with .push()
console.log("\nNon-determined array size with .push()");
console.log("%cSize | Time (ms)", "font-weight: bold");
for (let x of [1000, 1001, 10000, 10001, 100000, 100001, 10_000_000, 10_000_001]) {
  const iterations = 10; // number of times to run the test
  const start = performance.now();
  for (let i = 0; i < iterations; i++) {
    arr = [];
    for (let j = 0; j < x; j++) {
      arr.push(Object.assign({}, foo));
    }
  }
  const end = performance.now();
  console.log(`%c${x} | ${(end - start) / iterations}`, "color: red");
}