Easy

1. Reverse a String(ES6)

Take the string provided and reverse the order of the characters, must be a string when done.

const revstr = (str) => str.split("").reverse().join("");

console.log(revstr("abcdefghijklmnopqrst"));

2. Factorialize(ES6)

Return the factorial of the provided integer. If the integer is represented with the letter n, a factorial is the product of all positive integers less than or equal to n. Factorials are often represented with the shorthand notation n!

For example: 5! = 1 x 2 x 3 x 4 x 5 = 120

const factorialize = (num) => {
  let result = 1;
  for (let i = 1; i <= num; i++) {
    result *= i;
  }
  return result;
};

console.log(factorialize(5));

3. Palindrome(ES6)

Return true if the given string is a palindrome. Otherwise, return false. A palindrome is a word or sentence that’s spelled the same way both forward and backward, ignoring punctuation, case, and spacing.

Note. You’ll need to remove all non-alphanumeric characters (punctuation, spaces and symbols) and turn everything lower case in order to check for palindromes.

We’ll pass strings with varying formats, such as “racecar”, “RaceCar”, and “race CAR” among others.

const isPalindrome = (str) => {
  let reg = /[\W_]/g;
  let newStr = str.toLowerCase().replace(reg, "");

  const revString = newStr.split("").reverse().join("");
  return revString === newStr;
};

console.log(isPalindrome("racecar"));

4. Longest Word(ES6)

Return the length of the longest word in the provided sentence.

Your response should be a number.

Provided test cases:

findLongestWord(“May the force be with you”) should return 5

findLongestWord(“Google do a barrel roll”) should return 6

findLongestWord(“What if we try a super-long word such as otorhinolaryngology”) should return 19

const longestWord = (str) => {
  let words = str.split(" ");
  let longest = "";
  for (let word of words) {
    if (word.length > longest.length) longest = word;
  }
  return longest.length;

  //better way
  // return str.split(" ").sort((a, b) => {
  //   return b.length - a.length;
  // })[0];
};

console.log(longestWord("the cow jumped over the moon"));

5. Titlecase

Return the provided string with the first letter of each word capitalized. Make sure the rest of the word is in lower case. For the purpose of this exercise, you should also capitalize connecting words like “the” and “of”.

const titleCase = (str) => {
  return str
    .toLowerCase()
    .split(" ")
    .map((word) => word[0].toUpperCase() + word.substr(1))
    .join(" ");
};

console.log(titleCase("the cow jumped over the moon again"));

6. FizzBuzz 2 ways

FizzBuzz is the classic algorithm everyone should have. Here I have it run 2 ways. The difference is the first way prints out all numbers up to a limit and the second way allows the user to check a specific number.

const fizzbuzz = () => {
  for (let i = 1; i <= 100; i++) {
    if (i % 15 === 0) {
      console.log("fizzbuzz");
    } else if (i % 3 === 0) {
      console.log("fizz");
    } else if (i % 5 === 0) {
      console.log("buzz");
    } else {
      console.log(i);
    }
  }
};

console.log(fizzbuzz());

FizzBuzz with user checking a specific number:

const fizzbuzz = (num) => {
  if (num % 15 === 0) return "fizzbuzz";
  if (num % 3 === 0) return "fizz";
  if (num % 5 === 0) return "buzz";
  return num;
};

console.log(fizzbuzz(33));

Medium

1. Equal Sides Of An Array

You are going to be given an array of integers. Your job is to take that array and find an index N where the sum of the integers to the left of N is equal to the sum of the integers to the right of N. If there is no index that would make this happen, return -1.

For example:

Let's say you are given the array [1,2,3,4,3,2,1]: Your function will return the index 3, because at the 3rd position of the array, the sum of left side of the index ({1,2,3}) and the sum of the right side of the index ({3,2,1}) both equal 6.

function findEvenIndex(arr) {
  for (var i = 1; i < arr.length - 1; i++) {
    if (
      arr.slice(0, i).reduce((a, b) => a + b) ===
      arr.slice(i + 1).reduce((a, b) => a + b)
    ) {
      return i;
    }
  }
  return -1;
}

ES6 Method

const findEvenIndex = (arr) => {
  return arr.findIndex((item, index) => {
    return (
      arr.slice(0, index).reduce((a, b) => a + b, 0) ===
      arr.slice(index + 1).reduce((a, b) => a + b, 0)
    );
  });
};
console.log(findEvenIndex([1, 2, 3, 4, 3, 2, 1]));

2. Unique In Order

Implement the function unique_in_order which takes as argument a sequence and returns a list of items without any elements with the same value next to each other and preserving the original order of elements.

const uniqueInOrder = (it) => {
  let result = [];
  let last;
  for (var i = 0; i < it.length; i++) {
    if (it[i] !== last) {
      result.push((last = it[i]));
    }
  }

  return result;
};

ES6 Method

const uniqueInOrder = (d) => [...d].filter((x, i, a) => x != a[i + 1]);

console.log(uniqueInOrder("AAAABBBCCDAABBB"));

3. Largest Number in an Array

Return an array consisting of the largest number from each provided sub-array. For simplicity, the provided array will contain exactly 4 sub-arrays.

Remember, you can iterate through an array with a simple for loop, and access each member with array syntax arr[i].

const larg = (arr) => {
  let maxes = [];
  for (let i = 0; i < arr.length; i++) {
    let tempMax = arr[i][0];
    for (let j = 0; j < arr[i].length; j++) {
      let currel = arr[i][j];
      if (currel >= tempMax) {
        tempMax = currel;
      }
    }
    maxes.push(tempMax);
  }
  return maxes;
};

ES6 Method

const larg = (arr) => {
  return arr.map((subArr) => Math.max.apply(null, subArr));
};

console.log(
  larg([
    [5, 40, 6, 7],
    [1, 6, 80, 8],
    [3, 60, 9, 8],
    [50, 4, 1, 6],
  ])
);

Github