JavaScript Exercises: Intermediate for Loop Challenges
Sharpen your JavaScript skills with these intermediate exercises that focus on using traditional for loops within functions to manipulate strings, numbers, objects, and arrays. Each exercise requires you to write a function that returns the output.
Exercises
1. Sum of an Array
Question: Write a function sumArray that takes an array of numbers and returns the sum of all elements.
Required Output for [1, 2, 3, 4]: 10
Required Output for []: 0
Required Output for [1]: 1
2. Reverse String
Question: Write a function reverseString that takes a string and returns it reversed.
Required Output for “hello”: "olleh"
Required Output for “world”: "dlrow"
Required Output for “”: ""
3. Find Min and Max
Question: Write a function findMinMax that returns the minimum and maximum of an array of numbers as an object { min, max }.
Required Output for [2, 3, 1, 4]: { min: 1, max: 4 }
Required Output for []: { min: undefined, max: undefined }
Required Output for [1]: { min: 1, max: 1 }
4. Count Characters
Question: Write a function countChars that takes a string and returns an object with the counts of each character.
Required Output for “hello”: { h: 1, e: 1, l: 2, o: 1 }
Required Output for “world”: { w: 1, o: 1, r: 1, l: 1, d: 1 }
Required Output for “”: {}
Required Output for “a”: { a: 1 }
5. Multiplication Table
Question: Write a function multiplicationTable that takes a number and returns its multiplication table up to 10 as an array.
Required Output for 3: [3, 6, 9, 12, 15, 18, 21, 24, 27, 30]
Required Output for 5: [5, 10, 15, 20, 25, 30, 35, 40, 45, 50]
Required Output for 7: [7, 14, 21, 28, 35, 42, 49, 56, 63, 70]
6. Filter Odd Numbers
Question: Write a function filterOdds that filters out odd numbers from an array and returns the remaining numbers.
Required Output for [1, 2, 3, 4, 5]: [1, 3, 5]
Required Output for [1, 2, 3, 4, 5]: [2, 4]
Required Output for []: []
7. Convert to Camel Case
Question: Write a function toCamelCase that converts a string of words separated by spaces or underscores to camelCase.
Required Output for “hello world”: "helloWorld"
Required Output for “hello_world”: "helloWorld"
8. Rotate Array
Question: Write a function rotateArray that rotates an array to the right by a given number of steps.
Required Output for ([1, 2, 3, 4, 5], 2): [4, 5, 1, 2, 3]
Required Output for ([1, 2, 3, 4, 5], 3): [3, 4, 5, 1, 2]
9. Flatten Array
Question: Write a function flattenArray that flattens an array of arbitrarily nested arrays of integers into a flat array.
Required Output for [1, [2, [3, 4], 5]]: [1, 2, 3, 4, 5]
Required Output for [1, 2, [3, [4, [5, [6, 7]]]]]: [1, 2, 3, 4, 5, 6, 7]
10. Find Duplicate Numbers
Question: Write a function findDuplicates that finds and returns duplicate numbers from an array.
Required Output for [1, 2, 3, 2, 4, 3]: [2, 3]
Required Output for [1, 2, 3, 4, 5]: []
11. Capitalize Words
Question: Write a function capitalizeWords that takes a string and capitalizes the first letter of each word.
Required Output for “capitalize every word”: "Capitalize Every Word"
Required Output for “hello world”: "Hello World"
12. Unique Characters
Question: Write a function uniqueChars that checks if a string contains only unique characters and returns true or false.
Required Output for “abcdef”: true
Required Output for “hello”: false
13. Array Intersection
Question: Write a function arrayIntersection that returns the intersection of two arrays.
Required Output for ([1, 2, 3], [2, 3, 4]): [2, 3]
Required Output for ([1, 2, 3], [4, 5, 6]): []
14. Sum of Digits
Question: Write a function sumDigits that takes a number and returns the sum of its digits.
Required Output for 1234: 10
Required Output for 9876: 30
15. Is Anagram
Question: Write a function isAnagram that checks if two provided strings are anagrams of each other.
Required Output for (“listen”, “silent”): true
Required Output for (“hello”, “world”): false
16. Remove Specific Element
Question: Write a function removeElement that takes an array and an element to remove, returning the array without that element.
Required Output for ([1, 2, 3, 4, 5], 3): [1, 2, 4, 5]
Required Output for ([1, 2, 3, 4, 5], 6): [1, 2, 3, 4, 5]
17. Count Words
Question: Write a function countWords that takes a string and returns the number of words in the string.
Required Output for “This is a test string”: 5
Required Output for “”: 0
18. Sort Numbers
Question: Write a function sortNumbers that takes an array of numbers and returns a sorted array in ascending order using a sorting algorithm implemented with a for loop.
Required Output for [34, 7, 23, 32, 5]: [5, 7, 23, 32, 34]
Required Output for []: []
19. Are Arrays Equal
Question: Write a function areArraysEqual that checks if two arrays contain the same elements in the same order.
Required Output for ([1, 2, 3], [1, 2, 3]): true
Required Output for ([1, 2, 3], [3, 2, 1]): false
20. Find Longest Consecutive Sequence
Question: Write a function longestConsecutive that finds the longest sequence of consecutive integers in an unsorted array.
Required Output for [100, 4, 200, 1, 3, 2]: 4 (The sequence is [1, 2, 3, 4])
Conclusion
By practicing these exercises you will be able to use for loops and for...of loops to manipulate strings, numbers, objects, and arrays. You will also be able to use string methods to manipulate and manipulate strings.