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We have an array of elements that contains both truth and false values. Our job is to write a function that returns an array with indices of those elements which are NaN in the original array.NaN !== NaNThe datatype of NaN is actually number. Although NaN is a falsy value, it has a peculiar property that no other datatype or variable has. It’s that the expression NaN === NaN yields false. And it’s only in the case of NaN that its false.So, we can use this behavior to our good and pick out NaN value index. The code for this ... Read More
Let’s say, we have two arrays both containing String literals, one of which is required to sort alphabetically, but if this array, the one we have to sort contains some words from the other array, those words should appear at the very top and the rest of the element should be sorted alphabetically.Let’s write a function, say excludeSorting(arr, ex) where arr is the array to be sorted and ex is the array of strings that should appear at top in arr (if they appear in arr).Exampleconst arr = ['apple', 'cat', 'zebra', 'umbrella', 'disco', 'ball', 'lemon', 'kite', 'jack', 'nathan']; const toBeExcluded ... Read More
Let’s say, we have to write a function that takes in a number and returns an array of numbers with elements as the digits of the number but in reverse order. We will convert the number into a string, then split it to get an array of strings of digit, then we will convert the string into numbers, reverse the array and finally return it.Following is our function that takes in a number to be reversed −const reversifyNumber = (num) => { const numString = String(num); return numString.split("").map(el => { return +el; }).reverse(); };Exampleconst ... Read More
We have to write a function that generates a random color between two given colors. Let’s tackle this problem in parts −First → We write a function that generates a random number between two given numbers.Second → Instead of using the hex scale for random color generation, we will map the hex to 0 to 15 decimal scale and use that instead.Lastly → We loop over any of the given color strings and generate a random color.Exampleconst randomBetween = (a, b) => { const max = Math.max(a, b); const min = Math.min(a, b); return Math.floor(Math.random() * (max ... Read More
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 have to write a function that takes in an array and returns an object with two properties namely positive and negative. They both should be an array containing all positive and negative items respectively from the array.This one is quite straightforward, we will use the Array.prototype.reduce() method to pick desired elements and put them into an object of two arrays.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 splitArray = (arr) => { ... 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