RS-JS-core-interview.js

// *** Variables, Hoisting, Closures ***

// *Understanding of scope*
(function () {})();

(function () {
  for (var vari = 5; vari > 0; vari--) {}

  for (let leti = 5; leti > 0; --leti) {}

  {
    const consti = 5;
  }

  console.assert(myEq([vari, leti, consti]), [0, 0, 5]);
})();

// *Understanding of hoisting*
(function () {
  let test = 'outer';

  someFunction();

  const test2 = 'outer2';

  function someFunction() {
    console.assert(test === 'outer');
    console.assert(test2 === 'outer2');
    var test = 'inner';
  }
})();

// *Closure*
(function () {
  var array = [1, 2, 3, 4];
  for (var index = 0; index < array.length; index++) {
    setTimeout(function () {
      console.assert(typeof array[index] === 'number');
    }, 0);
  }
})();

// *let vs const vs var*
// ???

// *Context*
(function () {
  var bob = {
    name: 'Bob',
    // sayName: () => {
    sayName: function () {
      return this.name;
    },
  };
  var alice = {
    name: 'Alice',
  };
  var bobSayName = bob.sayName;
  console.assert(bobSayName() === 'Bob'); // 1

  alice.bobSayName = bobSayName;
  console.assert(alice.bobSayName() === 'Alice'); // 2

  console.assert(bobSayName.call(alice) === 'Alice'); // 3

  console.assert(bobSayName.bind(bob).call(alice) === 'Alice'); // 4
})();


// *** Knowledge of the Dom Events ***
// *Capturing*
// *Bubbling*
// *Event Delegation*
// *PreventDefault, stopPropagation, stopImmediatePropagation*
// *addEventListener*

// Open link and complete tasks - https://stackblitz.com/edit/rs-dom-events?file=index.js


// *** Knowledge of the Event Loop ***
// *What is Event Loop*
// *Promises & Microtasks*

(function () {
  var stack = [];

  stack.push(1);
  setTimeout(() => stack.push(2), 1000);
  setTimeout(() => stack.push(3), 0);
  Promise.resolve(4).then(stack.push.bind(stack));
  stack.push(5);

  setTimeout(() => {
    console.assert(myEq(stack, [1, 2, 3, 4, 5]));
  }, 5000);
})();

(function () {
  const stack = [];
  new Promise(function (res, rej) {
    throw 'My-Exeption';
  })
    .catch(function (ex) {
      stack.push('catched');
    })
    .then(
      function (res) {
        stack.push('then');
      },
      function (rej) {
        stack.push('catched');
      },
    );

  setTimeout(() => console.assert(myEq(stack, ['catched', 'catched'])), 1000);
})();

// *Knowledge of inheritance and classes*

/*
// Fix how class inheritance was transpiled
class CA {
  static staticMethodA() {
    return 42;
  }
  constructor(name = 'default name') {
    this.name = name;
  }
  methodA() {
    return this.name;
  }
}
class CB extends CA {
  methodB() {
    return 43;
  }
}
*/

(function () {
  function CA(name = 'default name') {
    this.name = name;
  }

  CA.prototype.methodA = () => {
    return this.name;
  };

  function CB() {}

  CB.prototype = CA.prototype;
  CB.prototype.methodB = () => {
    return 43;
  };
})();