async-js.js

function setNameAsync(setName) {
  // how do you set a name after 2sec. pause ?
  setTimeout(setName, 2000);
}

const user = {
  name: 'Bill',
  setName: function(name) {
    this.name = name;
    console.log(this.name);
  }
};

setNameAsync(user.setName);


Promise.resolve(1)
  .then((x) => x + 1)
  .then((x) => { throw new Error('My Error') })
  .catch(() => 1)
  .then((x) => x + 1)
  .then((x) => console.log(x))
  .catch(console.error)

const getRandomPromise = index => new Promise(resolve => {
	const timeout = Math.floor(Math.random() * 1000);
	setTimeout(() => {
		console.log(`[${ i }] Ended up after ${ timeout }`);
		resolve();
    }, timeout);
});
const promiseFactory = (_, i) => getRandomPromise(index);

const promises = Array.from(new Array(10), promiseFactory);


const getRandomPromise = index => new Promise((resolve, reject) => {
	const timeout = Math.floor(Math.random() * 1000);
	setTimeout(() => {
        // Randomly throw error
        if (timeout > 800) {
            reject(new Error(`[${ index }] Random Promise rejection after ${ timeout }`));
        } else {
            resolve(`[${ index }] Ended up after ${ timeout }`);
        }
    }, timeout);
});
const promiseFactory = (_, i) => getRandomPromise(i);
const promises = Array.from(new Array(10), promiseFactory);

Promise
    .all(promises)
    .then(x => console.log(x));

es-6.js

const foo = () => let a = 3;

const foo = () => { a: 3 };
const bar = foo();
console.log(bar.a);

for (const i = 0; i < 10; i++) {
  setTimeout(() => { console.log(i) },100)
}

var a = 2;
{
  const a = 3;
  {
    console.log(a); 
  }
}

const foo = function(a = (function(a) { return a == null ? {} : a })(a)) {
  console.log(a);
}

foo(null);
foo(3);


/**
 * @type {Array<{id: number, name: string, email: string}>}
 */
var users = [
  {
    id: 1,
    name: "Robbi",
    email: "[email protected]"
  }
  // ...
];

users.reduce(function(map, user) {
  map[user.id] = user;
  return map;
}, {});


const data = [
    [
        1,
        'one'
    ],
    [
        2,
        'two',
        [
            4,
            'four'
        ]
    ],
    [
        3,
        'three'
    ]
];

js-functions-quiz.js

function bar() {
    return foo;
    foo = 10;
    function foo() {}
    var foo = '11';
}
alert(typeof bar());

(function(){
  return typeof arguments;
})();

var x = 1;
if (function f(){}) {
    x += typeof f;
}
x;

(function f(){
    function f(){ return 1; }
    return f();
    function f(){ return 2; }
})();

(function() {
    if (true) {
        var a = 5;
    }
    alert(a);
})();

function sum(a, b, c) {
    return a + b + c;
}

(function(a, b, c) {
  return a + b + c;
}).call(context, [ arg1, arg2, arg3 ]);

(function(a, b, c) {
  return a + b + c;
}).apply(context, [ arg1, arg2, arg3 ]);

(function(a, b, c) {
  return a + b + c;
}).bind(context, [ arg1, arg2, arg3 ]);

(function(a, b, c) {
  return a + b + c;
})([ arg1, arg2, arg3 ]);

for (var i = 0; i < 10; i++) {
  setTimeout(function() {
    console.log(i);
  }, i);
}

for (var i = 0; i < 10; i++) {
  setTimeout((function(ii) {
    return function() {
      console.log(ii)
    }
  })(i), i);
}

js-grammar-quiz.js

"455" - 4;

[, 'me', 42]

!!!0 ? !!1 === !!'false' : 1 + '1'

=== () || = &&