We are required to write a recursive function, say pickString that takes in a string that contains a combination of alphabets and numbers and returns a new string consisting of only alphabets.For example, If the string is ‘dis122344as65t34er’, The output will be: ‘disaster’Therefore, let’s write the code for this recursive function −Exampleconst str = 'ex3454am65p43le'; const pickString = (str, len = 0, res = '') => {    if(len < str.length){       const char = parseInt(str[len], 10) ? '' : str[len];       return pickString(str, len+1, res+char);    };    return res; }; console.log(pickString(str)); console.log(pickString('23123ca43n y43ou54 6do884 ... Read More

We have to write a function, say findPositions() that takes in two arrays as argument. And it should return an array of the indices of all the elements of the second array present in the first array.For example −If the first array is [‘john’, ‘doe’, ‘chris’, ‘snow’, ‘john’, ‘chris’], And the second array is [‘john’, chris]Then the output should be −[0, 2, 4, 5]Therefore, let’s write the code for this function. We will use a forEach() loop here;Exampleconst values = ['michael', 'jordan', 'jackson', 'michael', 'usain', 'jackson', 'bolt', 'jackson']; const queries = ['michael', 'jackson', 'bolt']; const findPositions = (first, second) => ... Read More

We are required to write a function for arrays Array.prototype.remove(). It accepts one argument; it is either a callback function or a possible element of the array. If it’s a function then the return value of that function should be considered as the possible element of the array and we have to find and delete that element from the array in place and the function should return true if the element was found and deleted otherwise it should return false.Therefore, let’s write the code for this function −Exampleconst arr = [12, 45, 78, 54, 1, 89, 67]; const names = ... Read More

We have an array of Numbers that contains some positive and negative even and odd numbers. We are required to sort the array in ascending order but all the even numbers should appear before any of the odd number and all the odd numbers should appear after all the even numbers and obviously both sorted within.Therefore, for example −If the input array is −const arr = [-2, 3, 6, -12, 9, 2, -4, -11, -8];Then the output should be −[ -12, -8, -4, -2, 2, 6, -11, 3, 9]Therefore, let’s write the code for this sort function −Exampleconst arr = ... Read More

We have to write a function that takes in an object and a string literals array, and it returns the filtered object with the keys that appeared in the array of strings.For example − If the object is {“a”: [], “b”: [], “c”:[], “d”: []} and the array is [“a”, “d”] then the output should be −{“a”: [], “d”:[]}Therefore, let’s write the code for this function, We will iterate over the keys of the object whether it exists in the array, if it does, if shove that key value pair into a new object, otherwise we keep iterating and return ... Read More

We have to write a function that accepts a string and mirrors its alphabet. For example −If the input is ‘abcd’ The output should be ‘zyxw’The function simply takes every character and map to the that is (26 - N) alphabets away from it, where is the 1 based index of that alphabet like 5 for e and 10 for j.We will use the String.prototype.replace() method here, to match all the English alphabets irrespective of their case. The full code for this function will be −Exampleconst str = 'ABCD'; const mirrorString = str => {    const regex = /[A-Za-z]/g; ... Read More

Let’s say, we have an array that contains the score of some players in different sports. The scores are represented like this −const scores = [    {sport: 'cricket', aman: 54, vishal: 65, jay: 43, hardik: 88, karan:23},    {sport: 'soccer', aman: 14, vishal: 75, jay: 41, hardik: 13, karan:73},    {sport: 'hockey', aman: 43, vishal: 35, jay: 53, hardik: 43, karan:29},    {sport: 'volleyball', aman: 76, vishal: 22, jay: 36, hardik: 24, karan:47},    {sport: 'baseball', aman: 87, vishal: 57, jay: 48, hardik: 69, karan:37}, ];We have to write a function that takes in this array and returns a ... Read More

We have an array of objects, which further have nested objects like this −const arr = [{    id: 0, children: [] }, {       id: 1, children: [{       id: 2, children: [] }, {       id: 3, children: [{          id: 4, children: []       }]    }] }];Our job is to write a recursive function, say assignDepth() that takes in this array and assigns depth property to each nested object. Like the object with id 0 will have depth 0, id 1 will have depth 1 ... Read More

A butterfly shuffled array in JavaScript is an array of Numbers that is sorted such that the numbers decrease as we approach the center of array and increase as we approach the end of array. The biggest number is placed at the very first index.Another variation of butterfly shuffled array is where the numbers increase towards the center and decrease towards the end. In this case the smallest number is placed at the very first index.For people who come from a Mathematics background, it’s somewhat relatable to the Guassian distribution.ExampleSuppose we have this array −const arr = [8, 2, 6, ... Read More

each_cons() - RubyThe each_cons() method of enumerable is an inbuilt method in Ruby that iterates for consecutive N elements starting from each element every time. If no block is given, it returns the enumerator.JS equivalent of each_cons()Suppose we have an array of Number literals (JS equivalent of Ruby’s enumerable in this case), the each_cons function is supposed to be an Array function that executes for each element of the array and accepts a number N (N