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We are required to write a function containsAll() that takes in two arguments, first an object and second an array of strings. It returns a boolean based on the fact whether or not the object contains all the properties that are mentioned as strings in the array.So, let’s write the code for this. We will iterate over the array, checking for the existence of each element in the object, if we found a string that’s not a key of object, we exit and return false, otherwise we return true.Here is the code for doing the same −Exampleconst obj = { ... Read More
We are required to write a function that takes in two numbers and returns their product, but without using the (*) operator.Trick 1: Using Divide Operator TwiceWe know that multiplication and division are just the inverse of each other, so if we divide a number by other number’s inverse, won’t it be same as multiplying the two numbers?Let’s see the code for this −const a = 20, b = 45; const product = (a, b) => a / (1 / b); console.log(product(a, b));Trick 2: Using LogarithmsLet’s examine the properties of logarithms first −log(a) + log(b) = log(ab)So, let’s use this ... Read More
We are given an object that contains some random properties, including some numbers, boolean, strings and the object itself.We are required to write a function that takes in the object as first argument and a string as second argument, possible value for second argument is a name of any data type in JavaScript like number, string, object, boolean, symbol etc.Our task is to delete every property of type specified by the second argument. If the second argument is not provided, take ‘number’ as default.The full code for doing so will be −const obj = { name: 'Lokesh Rahul', ... Read More
Let’s say, we have an array of arrays, each containing some numbers along with some undefined and null values. We are required to create a new array that contains the sum of each corresponding sub array elements as its element. And the values undefined and null should be computed as 0.Following is the sample array −const arr = [[ 12, 56, undefined, 5 ], [ undefined, 87, 2, null ], [ 3, 6, 32, 1 ], [ undefined, null ]];The full code for this problem will be −Exampleconst arr = [[ 12, 56, undefined, 5 ... Read More
Let’s say, we have to write a function −replaceChar(str, arr, [char])Now, replace all characters of string str that are not present in array of strings arr with the optional argument char. If char is not provided, replace them with ‘*’.Let’s write the code for this function.The full code will be −Exampleconst arr = ['a', 'e', 'i', 'o', 'u']; const text = 'I looked for Mary and Samantha at the bus station.'; const replaceChar = (str, arr, char = '*') => { const replacedString = str.split("").map(word => { return arr.includes(word) ? word : char; }).join(""); ... Read More
Let’s say, we have an array of objects that contains data about the humidity over the seven days of a week. The data, however, sits randomly in the array right now. We are supposed to sort the array of objects according to the days like data for Monday comes first, then Tuesday, Wednesday and lastly Sunday.Following is our array −const weather = [{ day: 'Wednesday', humidity: 60 }, { day: 'Saturday', humidity: 50 }, { day: 'Thursday', humidity: 65 }, { day: 'Monday', humidity: 40 }, { day: 'Sunday', humidity: ... Read More
Let’s say, we are given an array of numbers that contains first n natural numbers, but one element appears twice in the array, so the total number of elements is n+1. Our job is to write a function that takes in the array and returns the number that appears twice in linear time.Method 1: Using Array.prototype.reduce()This is a bit trickier approach but the most compressed in terms of code written. First, let’s see the code for it −const arr = [1, 4, 8, 5, 6, 7, 9, 2, 3, 7]; const duplicate = a => a.reduce((acc, val, ind) => val+acc- ... Read More
We are required to write a function that takes in an array of numbers and returns the difference between its highest and lowest number.At first, create an array −const arr = [23, 54, 65, 76, 87, 87, 431, -6, 22, 4, -454];Now, find maximum and minimum values with Math.max() and Math.min() methods, respectively −const arrayDifference = (arr) => { let min, max; arr.forEach((num, index) => { if(index === 0){ min = num; max = num; }else{ min = Math.min(num, min); ... Read More
Let’s say, we are required to write a function that takes in two arrays and returns a new array that contains values in alternating order from first and second array. Here, we will just loop over both the arrays simultaneously picking values from them one after the other and feed them into the new array.The full code for doing the same will be −Exampleconst arr1 = [34, 21, 2, 56, 17]; const arr2 = [12, 86, 1, 54, 28]; let run = 0, first = 0, second = 0; const newArr = []; while(run < arr1.length + arr2.length){ if(first ... Read More
Let’s say, we have an array of strings in which each value each element has a dash (-), left to which we have our key and right to which we have our value. Our job is to split these strings and form an object out of this array.Here is the sample array −const arr = ["name-Rakesh", "age-23", "city-New Delhi", "jobType-remote", "language-English"];So, let’s write the code, it will loop over the array splitting each string and feeding it into the new objectThe full code will be −Exampleconst arr = ["name-Rakesh", "age-23", "city-New Delhi", "jobType-remote", "language-English"]; const obj = {}; arr.forEach(string => ... Read More