Question

Guess the outputs of the following code:

**Note - Code 2 and Code 3 require you to modify the code, instead of guessing the output.

// Code 1

(function(a){

  return (function(){

    console.log(a);

    a = 23;

  })()

})(45);

// Code 2

// Each time bigFunc is called, an array of size 700 is being created,

// Modify the code so that we don't create the same array again and again

function bigFunc(element){

  let newArray = new Array(700).fill('?');

  return newArray[element];

}

console.log(bigFunc(599)); // Array is created

console.log(bigFunc(670)); // Array is created again

// Code 3

// The following code outputs 2 and 2 after waiting for one second

// Modify the code to output 0 and 1 after one second.

function randomFunc(){

  for(var i = 0; i < 2; i++){

    setTimeout(()=> console.log(i),1000);

  }

}

randomFunc();

Answer 1

Code 1 - Outputs 45 .

Even though a is defined in the outer function, due to closure the inner functions have access to it.

Code 2 - This code can be modified by using closures,

function bigFunc(){

  let newArray = new Array(700).fill('?');

  return (element) => newArray[element];

}

let getElement = bigFunc(); // Array is created only once

getElement(599);

getElement(670);  

Code 3 - Can be modified in two ways:

Using let keyword:

function randomFunc(){

  for(let i = 0; i < 2; i++){

    setTimeout(()=> console.log(i),1000);

  }

}

randomFunc();

Using closure:

function randomFunc(){

  for(var i = 0; i < 2; i++){

  (function(i){

      setTimeout(()=>console.log(i),1000);

    })(i);

  }

}

randomFunc();