SOURCE

const a = [];
let obj = {};
let map = new Map();
let b;

function init() {
    for (let i = 0; i < 99999999; i++) {
        a.push(i);
    }
}


function test(title, callback) {
    let t = (new Date()).getTime();
    callback();
    console.log(title + ' ->', ((new Date()).getTime() - t) + ' ms');
}

// init();

test('let', () => {
    let i = 10;
})
test('const', () => {
    const i = 10;
})