Coding Bootcamp JavaScript (JS)

Our Coding bootcamp javascript 2020

This held in 10 days. (Due to the coronavirus, this event was also done online)

Members of our Bootcamp

88 members (Mostly from India and canada)

Questions

Question: How to find max and min number in an array using reduce method ?

Question: Try to fill in the blanks. (Without any changes) You can add some codes instead of ?????????. Answer: The output must be true.

const x = ?????????;
console.log(x == 5 && x == 25 && x == 125); // true

Note: Please not search and google it. No time limit, anyone can think and try for this.

Question: Consider the two functions below. Will they both return the same thing? Why and not?

function t1()
{
  return {
      bar: "hello"
  };
}
function t2()
{
  return
  {
      bar: "hello"
  };
}

Test:

console.log("t1:");
console.log(t1());
console.log("t2:");
console.log(t2());

Are you familiar with data type and operators? If you think you are a js expert, think about this:

Question: What will the code below output? Explain your answer. (guess the output)

console.log(0.1 + 0.2);
console.log(0.1 + 0.2 == 0.3);

Question: Write a add method which will work properly when invoked using either syntax below.

console.log( add(2)(3) );  // Outputs: 5
console.log( add(4)(6) );  // Outputs: 10
console.log( add(6)(6) );  // Outputs: 12

Okay, we go to next step:

Question: Write a add method which will work properly when invoked using either syntax below.

console.log( add(0) );  // Outputs: 0
console.log( add(2) );  // Outputs: 2
console.log( add(6) );  // Outputs: 6
console.log( add(2)(3) );  // Outputs: 5
console.log( add(4)(6) );  // Outputs: 10
console.log( add(6)(6) );  // Outputs: 12

But we have to expert in it to be sure of them. So trying... 👍

What about this? var cause a different in this case or no?

const myNumber = '3';
(function (callback) {
  console.log(myNumber);
  var myText = 'hello';
  callback();
})(function () {
    console.log(myNumber);
    console.log(myText);
  })

So it will be interest at now:

const myNumber = '3';
(function (callback) {
  console.log(myNumber);
  myText = 'hello';
  callback();
})(function () {
    console.log(myNumber);
    console.log(myText);
  })

Guess it.

Question: What will the following code output and why?

var b = 1;
function outer(){
    var b = 2
    function inner(){
        b++;
        let b = 5;
        console.log(b)
    }
    inner();
}
outer();

Question: What will the following code output and why?

var b = 1;
function outer(){
     var b = 2
    function inner(){
        b++;
        var b = 5;
        console.log(b)
    }
    inner();
}
outer();

Question: Guess output

console.log(color);
const color = '#aaa';

Question: Guess output

console.log(color);
var color = '#aaa';

Question: Guess output

console.log(color);
let color = '#aaa';

Question: Guess output

function square(a = 4) {
  return a * a;
}
console.log( square() );

Question: Guess output

var a=4;
function square(a = a) {
  return a * a;
}
console.log( square() );
console.log( square(2) );

Question: Guess output

let a=4;
function square(a = a) {
  return a * a;
}
console.log( square() );
console.log( square(2) );

Question: Guess output

const a=4;
function square(a = a) {
  return a * a;
}
console.log( square() );
console.log( square(2) );

Question:

function test(someVal) {
  typeof variable; // first question
  if (someVal) {
    typeof variable; // second question
    let variable;
  }
}
test(true);

Question: What will the code below output to the console and why?

(function(){
  var a = b = 3;
})();
console.log("a defined? " + (typeof a !== 'undefined'));
console.log("b defined? " + (typeof b !== 'undefined'));

Question: What will the code below output to the console and why?

var myObject = {
    foo: "bar",
    func: function() {
        var self = this;
        console.log("outer func:  this.foo = " + this.foo);
        console.log("outer func:  self.foo = " + self.foo);
        (function() {
            console.log("inner func:  this.foo = " + this.foo);
            console.log("inner func:  self.foo = " + self.foo);
        }());
    }
};
myObject.func();

Question: In what order will the numbers 1-4 be logged to the console when the code below is executed? Why? Guess order and why?

(function() {
    console.log(1); 
    setTimeout(function(){console.log(2)}, 1000); 
    setTimeout(function(){console.log(3)}, 0); 
    console.log(4);
})();

Question: Tell output of variables:

var a = b = 3;

What's Palindrome? A palindrome is a word, number, phrase, or other sequence of characters which reads the same backward as forward, such as madam, racecar. There are also numeric palindromes, including date/time stamps using short digits 11/11/11 11:11 and long digits 02/02/2020.

Question: Write a simple function that returns a boolean indicating whether or not a string is a palindrome.

Test case:

level => true
levels => false

Question: guess the d value

var d = {};
[ 'zebra', 'horse' ].forEach(function(k) {
  d[k] = undefined;
});
console.log (d)