Javascript Articles - Page 329 of 534

We have to write a function that takes in an object with many keys and replaces all false values with a dash (‘ - ’). We will simply iterate over the original object, checking for the keys that contain false values, and we will replace those false values with ‘-’ without consuming any extra space (i.e., in place)Exampleconst obj = {    key1: 'Hello',    key2: 'World',    key3: '',    key4: 45,    key5: 'can i use arrays',    key6: null,    key7: 'fast n furious',    key8: undefined,    key9: '',    key10: NaN, }; const swapValue = ... Read More

We have to write a function, say padSting() that takes in two arguments, first is a string and second is a number. The length of string is always less than or equal to the number. We have to insert some random numbers at the end of the string so that its length becomes exactly equal to the number and we have to return the new string.Therefore, let’s write the code for this function −Exampleconst padString = (str, len) => {    if(str.length < len){       const random = Math.floor(Math.random() * 10);       return padString(str + random, ... Read More

We have an array that contains String and number mixed data types, we have to write a sorting function that sorts the array so that the NaN values always end up at the bottom. The array should contain all the normal numbers first followed by string literals and then followed by NaN numbers.We know that the data type of NaN is “number”, so we can’t check for NaN like !number && !string. Moreover, if we simply check the tautology and falsity of elements then empty strings will also satisfy the same condition which NaN or undefined satisfies.Check for NaNSo how ... Read More

We are required to make a function that accepts an array of arrays, and returns a new array with all elements present in the original array of arrays but remove the duplicate items.For example − If the input is −const arr = [    [12, 45, 65, 76, 76, 87, 98],    [54, 65, 98, 23, 78, 9, 1, 3],    [87, 98, 3, 2, 123, 877, 22, 5, 23, 67] ];Then the output should be single array of unique elements like this −[    12, 45, 54, 78, 9,    1, 2, 123, 877, 22,    5, 67 ]Exampleconst arr = [    [12, 45, 65, 76, 76, 87, 98],    [54, 65, 98, 23, 78, 9, 1, 3],    [87, 98, 3, 2, 123, 877, 22, 5, 23, 67] ]; const getUnique = (arr) => {    const newArray = [];    arr.forEach((el) => newArray.push(...el));    return newArray.filter((item, index) => {       return newArray.indexOf(item) === newArray.lastIndexOf(item);    }); }; console.log(getUnique(arr));OutputThe output in the console will be −[    12, 45, 54, 78, 9,    1, 2, 123, 877, 22,    5, 67 ]

We are required to write a function, say getIndex() that takes in an array arr, a string / number literal txt and a Number n. We have to return the index of nth appearance of txt in arr, . If txt does not appear for n times then we have to return -1.So, let’s write the function for this −Exampleconst arr = [45, 76, 54, 43, '|', 54, '|', 1, 66, '-', '|', 34, '|', 5, 76]; const getIndex = (arr, txt, n) => {    const position = arr.reduce((acc, val, ind) => {       if(val === txt){ ... Read More

We are required to write a function that takes in an array of numbers and a number, and it should remove all the occurrences of that number from the array inplace.Let’s write the code for this function.We will make use of recursion to remove elements here. The recursive function that removes all occurrences of an element from an array can be written like.Exampleconst numbers = [1,2,0,3,0,4,0,5]; const removeElement = (arr, element) => {    if(arr.indexOf(element) !== -1){       arr.splice(arr.indexOf(element), 1);       return removeElement(arr, element);    };    return; }; removeElement(numbers, 0); console.log(numbers);OutputThe output in the console will be −[ 1, 2, 3, 4, 5 ]

We have to write a recursive function that takes in a number n and returns the sum of all even numbers up to n.Let’s write the code for this function −Exampleconst recursiveEvenSum = (num, sum = 0) => {    num = num % 2 === 0 ? num : num - 1;    if(num){       return recursiveEvenSum(num - 2, sum+num);    }    return sum; }; console.log(recursiveEvenSum(12)); console.log(recursiveEvenSum(122)); console.log(recursiveEvenSum(23)); console.log(recursiveEvenSum(10)); console.log(recursiveEvenSum(19));OutputThe output in the console will be −42 3782 132 30 90

Let’s say, we have to write a function that takes in a Number and returns a boolean based on the fact whether or not the number is palindrome. One restriction is that we have to do this without converting the number into a string or any other data type.Palindrome numbers are those numbers which read the same from both backward and forward.For example −121 343 12321Therefore, let’s write the code for this function −Exampleconst isPalindrome = (num) => {    // Finding the appropriate factor to extract the first digit    let factor = 1;    while (num / factor ... Read More

Let’s say, the following is our array −const arr = [7, 2, 3, 4, 5, 7, 8, 12, -12, 43, 6];We are required to write a function that takes in the above array and returns an array with all the corresponding elements of array change to their negative counterpart (like 4 to -4, 6 to -6).If the element is already negative, then we should leave the element unchanged. Let’s write the code for this function −Exampleconst arr = [7, 2, 3, 4, 5, 7, 8, 12, -12, 43, 6]; const changeToNegative = (arr) => {    return arr.reduce((acc, val) => ... Read More

We are required to make a function that given an array of numbers and a string that can take any of the two values “odd” or “even”, adds the numbers which match that condition. If no values match the condition, 0 should be returned.For example −console.log(conditionalSum([1, 2, 3, 4, 5], "even")); => 6 console.log(conditionalSum([1, 2, 3, 4, 5], "odd")); => 9 console.log(conditionalSum([13, 88, 12, 44, 99], "even")); => 144 console.log(conditionalSum([], "odd")); => 0So, let’s write the code for this function, we will use the Array.prototype.reduce() method here −Exampleconst conditionalSum = (arr, condition) => {    const add = (num1, num2) ... Read More