Testing constact vs attribute access performance

performance-test.js

const range = n => Array.from(Array(n).keys());

function caseA() {
  const parentObject = { myObject: { items: range(500000) } };
  let hrstart = process.hrtime();
  let counter = 0;
  for (let i = 0, len = parentObject.myObject.items.length; i < len; i++) {
    counter += parentObject.myObject.items[i];
  }
  console.log("caseA total", counter);

  let hrend = process.hrtime(hrstart);
  console.info("Execution time (hr): %ds %dms", hrend[0], hrend[1] / 1000000);
}

function caseB() {
  const parentObject = { myObject: { items: range(500000) } };

  let hrstart = process.hrtime();
  let counter = 0;
  const { myObject } = parentObject;
  const { items } = myObject;
  for (let i = 0, len = items.length; i < len; i++) {
    counter += items[i];
  }
  console.log("caseB total", counter);
  let hrend = process.hrtime(hrstart);
  console.info("Execution time (hr): %ds %dms", hrend[0], hrend[1] / 1000000);
}

caseA();
caseB();