Interview Question By Interviewer

javascript-interview-questions.js

/**
 * @name - JavaScript Interview questions
 */
//====
/**
 * @name - TypeOf
 * @description - typeof [Number]
 */
console.log(typeof 25 === "number");
console.log(typeof 3.14 === "number");
console.log(typeof 69 === "number");

// log base 10
console.log(typeof Math.LN10 === "number");
console.log(typeof Infinity === "number");

// Despite being "Not-A-Number"
console.log(typeof NaN === "number");

// Wrapping in Number() function
console.log(typeof Number("100") === "number");

/**
 * @name - TypeOf
 * @description - typeof [String]
 */
console.log(typeof "" === "string");
console.log(typeof "bla" === "string");

// ES6 template literal
console.log(typeof `template literal` === "string");
console.log(typeof "1" === "string");
console.log(typeof typeof 1 === "string");

// Wrapping inside String() function
console.log(typeof String(1) === "string");

/**
 * @name - TypeOf
 * @description - typeof [Symbol]
 */
console.log(typeof Symbol); // function
console.log(typeof Symbol("")); // symbol
console.log(typeof Symbol(1)); // symbol

/**
 * @name - InstanceOf
 * @description - instanceOf [Object]
 */
console.log({} instanceof Object) // true
console.log(new Object() instanceof Object) // true

/**
 * @name - InstanceOf
 * @description - instanceOf [Function]
 */
const fn = function () { }
console.log(fn instanceof Function) // true
console.log(fn instanceof Function.constructor) // true

/**
 * @name - Hoisting
 * @description - Loop example
 */
for (var i = 10; i >= 0; i--) {
  setTimeout(() => console.log(i), 10);
}

// Hoisting Example 2

function x() {
  setTimeout(function () {
    console.log(i) // Output : 1
  })
  var i = 1
}

x()

/**
 * @name - Hoisting
 * @description - Example-1
 */

var b = 10;

function abc() {
  console.log(b); // undefined
  console.log(b++); // null
  var b = 3;
  console.log(b); // 3
}

abc();

/**
 * @name - Object Prototype
 * @description - __proto__ instanceOf Object
 * @link - https://dev.to/inambe/what-is-proto-javascript-191m
 */

const obj = new Object();
// console.log(obj.__proto__ instanceof Object); // false

// an object using object literal
const person = {
  name: "John",
  age: 30
};
// console.log(person.__proto__ === Object.prototype); // true

/**
* @name - Generator object
* @description - https://www.digitalocean.com/community/tutorials/understanding-generators-in-javascript
**/
let Obj = { * foo () { yield ({ a: '1' }) } }
// To accing the value 
Obj.foo().next() // Output :  {value: {a:'1'}, done: false}

/**
 * @name - Function Prototype
 * @description - __proto__ instanceOf Function
 * @link - ?
 */

let fn1 = function () { }
// fn1.__proto__ === Object // false
// fn1.__proto__ === Object.prototype // false
// console.log(fn1.__proto__ instanceof Function.prototype) // Error

/**
 * @name - Execution
 * @description - Execution order
 * @example - console vs process.nextTick vs setImmediate
 */

console.log("console first");
process.nextTick(() => console.log("process.nextTick")); // console second
setImmediate(() => console.log("setImmediate")); // console third

/**
 * @name - Snake_case to Camel_case convert
 */
const input = "this_is_a_snake_case_string";

// Solution 1
const camelCase = () => {
  return str.replace(/[_][a-z]/ig, (m) => {
    //  m => _i, _a, _s
    return m.toUpperCase().replace('_', '')
  }); 
}

// Solution 2
const camelCase = (str) => {
  return str.split('_').map((i, k) => k > 0 ? `${i.slice(0, 1).toString().toUpperCase()}${i.toString().slice(1,)}` : i).join('')
}

const output = camelCase(input);
console.log(output); // thisIsASnakeCaseString

/**
 * @name - Closure example
 */
function parent(name, message) {
  const val = 1;
  return function(param) {
    return { val, name, message, param}  
  }
}

// Function calls
let p = parent('joy', 'hello')
obj(true) // Output : { 1, 'joy', 'hello', true }

/**
 * @name - Difference
 * @description - Difference between Map() vs WeekMap()
 * @link - https://thisthat.dev/map-vs-weak-map/
 */

/**
 * @name - Difference
 * @description - Difference between Object.freez() vs Object.seal()
 * @link - https://communicode.io/object-freeze-vs-object-seal-javascript/
 */

/**
 * @question - How to utilize all cpus in node
 * @link - https://blog.devgenius.io/how-to-scale-a-nodejs-application-a51d3e8e2d36
 */

/**
 * @question - Difference beftween spawn vs fork in node.js
 * @link - https://www.freecodecamp.org/news/node-js-child-processes-everything-you-need-to-know-e69498fe970a
 * @link - https://www.geeksforgeeks.org/difference-between-spawn-and-fork-methods-in-node-js/
 */

/**
 * @question - Reactive programing in JavaScript
 * @link - https://javascript.plainenglish.io/reactive-programming-in-javascript-8373201a6618
 */
 
 /**
 * @question - Apply vs Bind vs Call
 * @link - https://github.com/rjoydip/javascript-concepts/tree/main/call-vs-apply-vs-bind
 */
 
 /**
 * @question - Hoisting
 * @link - https://github.com/rjoydip/javascript-concepts/tree/main/hoisting
 */
 
 /**
 * @question - Event Bubbling or Event Capturing
 * @link - https://github.com/rjoydip/javascript-concepts/tree/main/event-bubbling
 */
 
 /**
 * @question - How to secure node.js application
 * @link - ?
 */

 /**
 * @question - How to implement token authentication in node.js application
 * @link - ?
 */

 /**
 * @question - How to implement 2FA authentication in node.js application
 * @question - How 2FA authentication mechanisam works
 * @link - ?
 */
 
 /**
 * @question - Shallow vs Deep Copies
 * @link - https://www.freecodecamp.org/news/copying-stuff-in-javascript-how-to-differentiate-between-deep-and-shallow-copies-b6d8c1ef09cd
 */
 
 /**
 * @question - for-of vs for-in
 * @link - https://www.freecodecamp.org/news/javascript-loops-explained-for-loop-for
 */
 
 /**
 * @question  - How to create Node.js proxy server
 * @link - https://www.twilio.com/blog/node-js-proxy-server
 * @link - https://javascript.plainenglish.io/build-your-own-forward-and-reverse-proxy-server-using-node-js-from-scratch-eaa0f8d69e1f
 */

 /**
 * @question - Sets vs. WeakSets & Maps vs. WeakMap
 * @link - https://blog.logrocket.com/weakmap-weakset-understanding-javascript-weak-references/
 **/
 

react-interview-questions.js

/**
 * @name - React.js Interview questions
 */
//====

 /**
 * @question - Class level component vs. Functional component
 * @link - 
 **/
 
 /**
 * @question - Profiler in react.js
 * @link - 
 **/
 
 /**
 * @question - HOC or higher order component
 * @link - 
 **/
 
 /**
 * @question - Props drilling
 * @link - 
 **/
 
 /**
 * @question - React lifecycle
 * @link - 
 **/
 
 /**
 * @question - Component composition
 * @link - 
 **/
 
 /**
 * @question - ref and ForwardRef
 * @link - 
 **/