> For the complete documentation index, see [llms.txt](https://raffycastlee.gitbook.io/marcyannotes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://raffycastlee.gitbook.io/marcyannotes/codechallenge-curriculum/unit-2/20241016.md).

# CC-08: String Mutation and Array Iteration

with Carmen Salas • 2024/10/16

## Code Challenge

1. Declare a function called `stripUpperCase` that takes in a string argument consistenting of only alphabet characters and returns a new string with all uppercase letters removed. Note: You should not alter the input str, this function should return a new string.

```js
// this function is pure!
const stripUpperCase = (str) => {
  let res = str.split('');
  return res.filter((char) => {
    if (char == char.toLowerCase()) { return char; }
  }).join('');
}

// console.log('Hello');
// console.log(stripUpperCase('Hello')); // 'ello'
// console.log('SevenEleven');
// console.log(stripUpperCase('SevenEleven')); // 'evenleven'
// console.log('code challenge is fun');
// console.log(stripUpperCase("code challenge is fun")); // 'code challenge is fun'
```

2. Declare a function named `findLongestWord`, that takes an array of strings as an argument, and returns the longest string in the array. If there is more than one longest string, the function should return the **first** longest string that appears in the array. You must solve this without using any array methods.

```js
const findLongestWord = (arr) => {
  // without using array methods:
  // let res = '';
  // for (let word of arr) {
  //   if (word.length > res.length) { res = word; };
  // }
  // return res;
   
  // using reduce!
  return arr.reduce((res, curr) =>
   (curr.length > res.length) ? curr : res);
}

// console.log(findLongestWord(["The","quick","brown", "fox", "jumped", "over", "the", "lazy", "dog"]));
// console.log(findLongestWord(["jazzy", "jumpy", "quaky"])) //returns "jazzy"
```