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Javascript Articles
Page 12 of 534
Checking for centrally peaked arrays in JavaScript
ProblemWe are required to write a JavaScript function that takes in an array of numbers, arr, as the first and the only argument.Our function should check whether the input array is a centrally peaked array or not. If it is a centrally peaked array, we should return true, false otherwise.The conditions for being a centrally peaked array are −arr.length >= 3There exists some i with 0 < i < arr.length - 1 such that:arr[0] < arr[1] < ... arr[i-1] < arr[i]arr[i] > arr[i+1] > ... > arr[arr.length - 1]For example, if the input to the function is −const arr = ...
Read MoreFinding the nth element of the lucas number sequence in JavaScript
Lucas NumbersLucas numbers are numbers in a sequence defined like this −L(0) = 2 L(1) = 1 L(n) = L(n-1) + L(n-2)ProblemWe are required to write a JavaScript function that takes in a number n and return the nth lucas number.ExampleFollowing is the code −const num = 21; const lucas = (num = 1) => { if (num === 0) return 2; if (num === 1) return 1; return lucas(num - 1) + lucas(num - 2); }; console.log(lucas(num));OutputFollowing is the console output −24476
Read MoreConverting to hex and summing the numeral part in JavaScript
ProblemWe are required to write a JavaScript function that takes in a string. Our function should convert every character of the string to the hex value of its ascii code, then the result should be the sum of the numbers in the hex strings ignoring the letters present in hex.ExampleFollowing is the code −const str = "Hello, World!"; const toHexAndSum = (str = '') => { return str .split('') .map(c=>c.charCodeAt()) .map(n=>n.toString(16)) .join('') .split('') .filter(c=>'123456789'.includes(c)) .map(d=>parseInt(d)) .reduce((a, b)=>a+b, 0) }; console.log(toHexAndSum(str));OutputFollowing is the console output −91
Read MoreChecking for a Doubleton Number in JavaScript
Doubleton NumberWe will call a natural number a "doubleton number" if it contains exactly two distinct digits. For example, 23, 35, 100, 12121 are doubleton numbers, and 123 and 9980 are not.ProblemWe are required to write a JavaScript function that takes in a number and return true if it is a doubleton number, false otherwise.ExampleFollowing is the code −const num = 121212; const isDoubleTon = (num = 1) => { const str = String(num); const map = {}; for(let i = 0; i < str.length; i++){ const el = str[i]; if(!map.hasOwnProperty(el)){ ...
Read MoreConverting number of corresponding string without using library function in JavaScript
ProblemWe are required to write a JavaScript function that takes in a number n and converts it to the corresponding string without using the inbuilt functions String() or toString() or using string concatenation.ExampleFollowing is the code −const num = 235456; const convertToString = (num) => { let res = ''; while(num){ res = (num % 10) + res; num = Math.floor(num / 10); }; return res; }; console.log(convertToString(num));OutputFollowing is the console output −235456
Read MoreFinding quarter based on month index in JavaScript
ProblemWe are required to write a JavaScript function that takes in the 1-based month index and return the quarter, which the month falls in.ExampleFollowing is the code −const month = 7; const findQuarter = (month = 1) => { if (month
Read MoreFinding whether a number is triangular number in JavaScript
Triangular NumberTriangular number is the number of points that can fill an equilateral triangle.For instance − 9 is a triangular number which makes an equilateral triangle with each side of 4 units.ProblemWe are required to write a JavaScript function that takes in a number and returns true if its a triangular number, false otherwise.ExampleFollowing is the code −const num = 9; const isTriangular = (num = 1) => { let i = 4; if(num === 1){ return true; }; if(num === 3){ return true; }; while(((3 * 1) - 3)
Read MoreConverting miles per gallon to kilometer per liter in JavaScript
ProblemWe are required to write a JavaScript function that takes in a number in miles/gallon and return its equivalent km/litre.ExampleFollowing is the code −const num = 25; const converter = (mpg) => { let LITRES_PER_GALLON = 4.54609188; let KILOMETERS_PER_MILE = 1.609344; const ratio = KILOMETERS_PER_MILE / LITRES_PER_GALLON; return Math.round(100 * mpg * ratio) / 100; }; console.log(converter(num));OutputFollowing is the console output −8.85
Read MoreConverting a string to NATO phonetic alphabets in JavaScript
ProblemWe are required to write a JavaScript function that takes in a string and converts it into NATO phonetic alphabet.The 26 code words are as follows: Alfa, Bravo, Charlie, Delta, Echo, Foxtrot, Golf, Hotel, India, Juliett, Kilo, Lima, Mike, November, Oscar, Papa, Quebec, Romeo, Sierra, Tango, Uniform, Victor, Whiskey, X-ray, Yankee, Zulu.ExampleFollowing is the code −const str = 'this is simple string'; const convertToNato = (str = '') => { let nato = { a: 'Alfa', b: 'Bravo', c: 'Charlie', d: 'Delta', e: 'Echo', ...
Read MoreFinding number plate based on registration number in JavaScript
ProblemThe car registering system of a city N assigns two types of numbers −The Customer ID − a natural number between 0 and 17558423 inclusively, which is assigned to the car buyers in the following order: the first customer receives ID 0, the second customer receives ID 1, the third customer receives ID 2, and so on;Number Plate − assigned to the car and contains the series ( three Latin lowercase letters from a to z) and the serial number (three digits from 0 to 9).Example − aaa001. Each Number Plate is related to the given Customer ID. For example: ...
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