var vs let

benchmark.js

const benchmark = require('benchmark');

const suite = new benchmark.Suite();

suite.add('var loop', () => {
  var hi, i, list;

  list = [];
  for (i = 0; i < 50; ++i) {
    hi = { str: 'hi', i };
    list.push(hi);
  }
})
.add('let loop', () => {
  const list = [];
  for (let i = 0; i < 50; ++i) {
    const hi = { str: 'hi', i };
    list.push(hi);
  }
})
.on('cycle', event => {
  console.log(String(event.target));
})
.on('complete', function () {
  console.log('fastest is', this.filter('fastest').map('name'));
})
.run({ async: true });