We are required to write a JavaScript function that takes in a string and returns a new string with only the words that appeared for more than once in the original string.For example: If the input string is −const str = "big black bug bit a big black dog on his big black nose";Then the output should be −const output = "big black";ExampleLet’s write the code for this function −const str = "big black bug bit a big black dog on his big black nose"; const findDuplicateWords = str => {    const strArr = str.split(" ");    const res ... Read More

We are required to write a JavaScript function that takes in two 2-D arrays of numbers and returns their matrix multiplication result.Let’s say the following are our two matrices −// 5 x 4 let a = [    [1, 2, 3, 1],    [4, 5, 6, 1],    [7, 8, 9, 1],    [1, 1, 1, 1],    [5, 7, 2, 6] ]; // 4 x 6 let b = [    [1, 4, 7, 3, 4, 6],    [2, 5, 8, 7, 3, 2],    [3, 6, 9, 6, 7, 8],    [1, 1, 1, 2, 3, 6] ];ExampleLet’s ... Read More

We are required to write a JavaScript function that takes in a string and constructs a new string with all the uppercase characters converted to lowercase and all the lowercase characters converted to uppercase.Let’s write the code for this function −ExampleFollowing is the code −const str = 'The Case OF tHis StrinG Will Be FLiPped'; const isUpperCase = char => char.charCodeAt(0) >= 65 && char.charCodeAt(0) char.charCodeAt(0) >= 97 && char.charCodeAt(0) {    let newStr = '';    const margin = 32;    for(let i = 0; i < str.length; i++){       const curr = str[i];   ... Read More

We are required to write a JavaScript function that takes in a number and returns an array of all the prime numbers that exactly divide the input number.For example, if the input number is 18.Then the output should be −const output = [2, 3];ExampleLet’s write the code for this function −const num = 18; const isPrime = (n) => {    for(let i = 2; i {    const res = num % 2 === 0 ? [2] : [];    let start = 3;    while(start

We are required to write a JavaScript function that takes in a string and returns a new string with all the character of the original string just the whitespaces removed.ExampleLet’s write the code for this function −const str = "This is an example string from which all whitespaces will be removed"; const removeWhitespaces = str => {    let newStr = '';    for(let i = 0; i < str.length; i++){       if(str[i] !== " "){          newStr += str[i];       }else{          newStr += '';       };    };    return newStr; }; console.log(removeWhitespaces(str));OutputThe output in the console after removing whitespaces −Thisisanexamplestringfromwhichallwhitespaceswillberemoved

We are required to write a JavaScript function that takes in an array of numbers and uses the quick sort algorithm to sort it.QuickSortThis algorithm is basically a divide and conquer algorithm where we pick a pivot in every pass of loop and put all the elements smaller than pivot to its left and all greater than pivot to its right (if its ascending sort otherwise opposite)ExampleLet’s write the code for this function −const arr = [43, 3, 34, 34, 23, 232, 3434, 4, 23, 2, 54, 6, 54]; // Find a "pivot" element in the array to compare all ... Read More

In the English language, all these characters are considered as punctuations −'!', "," ,"\'" ,";" ,"\"", ".", "-" ,"?"We are required to write a JavaScript function that takes in a string and count the number of appearances of these punctuations in the string and return that count.ExampleLet’s write the code for this function −const str = "This, is a-sentence;.Is this a sentence?"; const countPunctuation = str => {    const punct = "!,\;\.-?";    let count = 0;    for(let i = 0; i < str.length; i++){       if(!punct.includes(str[i])){          continue;       };       count++;    };    return count; }; console.log(countPunctuation(str));OutputThe output in the console: −5

We are required to write a JavaScript function that takes in two 2-D arrays and returns a boolean based on the check whether the arrays are equal or not.The equality of these arrays, in our case, is determined by the equality of corresponding elementsBoth the arrays should have same number of rows and columns −arr1[i][j] === arr2[i][j]The above should yield true for all i between [0, number of rows] and j between [0, number of columns]ExampleLet’s write the code for this function −const arr1 = [    [1, 1, 1],    [2, 2, 2],    [3, 3, 3], ]; const ... Read More

TransposeThe transpose of a matrix (2-D array) is simply a flipped version of the original matrix (2-D array). We can transpose a matrix (2-D array) by switching its rows with its columns.Let’s say the following is our 2d array −const arr = [    [1, 1, 1],    [2, 2, 2],    [3, 3, 3], ];Let’s write the code for this function −ExampleFollowing is the code −const arr = [    [1, 1, 1],    [2, 2, 2],    [3, 3, 3], ]; const transpose = arr => {    for (let i = 0; i < arr.length; i++) {       for (let j = 0; j < i; j++) {          const tmp = arr[i][j];          arr[i][j] = arr[j][i];          arr[j][i] = tmp;       };    } } transpose(arr); console.log(arr);OutputThe output in the console: −[ [ 1, 2, 3 ], [ 1, 2, 3 ], [ 1, 2, 3 ] ]

We have an array of literals that contains some duplicate values appearing for many times like this −const arr = [1, 4, 3, 3, 1, 3, 2, 4, 2, 1, 4, 4];We are required to write a JavaScript function that takes in this array and pick out all the duplicate entries from the original array and only once.So, for the above array, the output should be −const output = [1, 4, 3, 2];ExampleLet’s write the code for this function −const arr = [1, 4, 3, 3, 1, 3, 2, 4, 2, 1, 4, 4]; const pickDuplicate = arr => { ... Read More