freeCodeCamp/curriculum/challenges/english/15-javascript-algorithms-and-data-structures-22/learn-functional-programming-by-building-a-spreadsheet/64496d80bc174a158c973080.md

id, title, challengeType, dashedName

id	title	challengeType	dashedName
64496d80bc174a158c973080	Step 25	0	step-25

--description--

Using ternary syntax, check if length is even using your isEven function. If it is, return the average of the number at the middle index and the number after that. If it's odd, return the number at the middle index – you'll need to round the middle value up.

--hints--

You should use the return keyword.

assert.match(code, /const\s+median\s*=\s*nums\s*=>\s*\{\s*const\s+sorted\s*=\s*nums\.slice\(\s*\)\.sort\(\s*\(\s*a\s*,\s*b\s*\)\s*=>\s*a\s*-\s*b\s*\)\s*\s*;?\s*const\s+length\s*=\s*sorted\.length\s*;?\s*const\s+middle\s*=\s*length\s*\/\s*2\s*-\s*1\s*;?\s*return/);

You should call your isEven() function after your return keyword.

assert.match(code, /const\s+median\s*=\s*nums\s*=>\s*\{\s*const\s+sorted\s*=\s*nums\.slice\(\s*\)\.sort\(\s*\(\s*a\s*,\s*b\s*\)\s*=>\s*a\s*-\s*b\s*\)\s*\s*;?\s*const\s+length\s*=\s*sorted\.length\s*;?\s*const\s+middle\s*=\s*length\s*\/\s*2\s*-\s*1\s*;?\s*return\s+isEven\(/);

You should pass your length variable to your isEven() call.

assert.match(code, /const\s+median\s*=\s*nums\s*=>\s*\{\s*const\s+sorted\s*=\s*nums\.slice\(\s*\)\.sort\(\s*\(\s*a\s*,\s*b\s*\)\s*=>\s*a\s*-\s*b\s*\)\s*\s*;?\s*const\s+length\s*=\s*sorted\.length\s*;?\s*const\s+middle\s*=\s*length\s*\/\s*2\s*-\s*1\s*;?\s*return\s+isEven\(\s*length\s*\)/);

You should use ternary syntax to check the truthiness of your isEven() call.

assert.match(code, /const\s+median\s*=\s*nums\s*=>\s*\{\s*const\s+sorted\s*=\s*nums\.slice\(\s*\)\.sort\(\s*\(\s*a\s*,\s*b\s*\)\s*=>\s*a\s*-\s*b\s*\)\s*\s*;?\s*const\s+length\s*=\s*sorted\.length\s*;?\s*const\s+middle\s*=\s*length\s*\/\s*2\s*-\s*1\s*;?\s*return\s+isEven\(\s*length\s*\)\s*\?/);

If the ternary is truthy, you should call your average() function.

assert.match(code, /const\s+median\s*=\s*nums\s*=>\s*\{\s*const\s+sorted\s*=\s*nums\.slice\(\s*\)\.sort\(\s*\(\s*a\s*,\s*b\s*\)\s*=>\s*a\s*-\s*b\s*\)\s*\s*;?\s*const\s+length\s*=\s*sorted\.length\s*;?\s*const\s+middle\s*=\s*length\s*\/\s*2\s*-\s*1\s*;?\s*return\s+isEven\(\s*length\s*\)\s*\?\s*average\(/);

You should pass an array to your average() function.

assert.match(code, /const\s+median\s*=\s*nums\s*=>\s*\{\s*const\s+sorted\s*=\s*nums\.slice\(\s*\)\.sort\(\s*\(\s*a\s*,\s*b\s*\)\s*=>\s*a\s*-\s*b\s*\)\s*\s*;?\s*const\s+length\s*=\s*sorted\.length\s*;?\s*const\s+middle\s*=\s*length\s*\/\s*2\s*-\s*1\s*;?\s*return\s+isEven\(\s*length\s*\)\s*\?\s*average\(\s*\[/);

The first element of the array passed to average() should be the element at the middle index of your sorted array.

assert.match(code, /const\s+median\s*=\s*nums\s*=>\s*\{\s*const\s+sorted\s*=\s*nums\.slice\(\s*\)\.sort\(\s*\(\s*a\s*,\s*b\s*\)\s*=>\s*a\s*-\s*b\s*\)\s*\s*;?\s*const\s+length\s*=\s*sorted\.length\s*;?\s*const\s+middle\s*=\s*length\s*\/\s*2\s*-\s*1\s*;?\s*return\s+isEven\(\s*length\s*\)\s*\?\s*average\(\s*\[\s*sorted\s*\[\s*middle\s*\]/);

The first element of the array passed to average() should be the element at the middle + 1 index of your sorted array.

assert.match(code, /const\s+median\s*=\s*nums\s*=>\s*\{\s*const\s+sorted\s*=\s*nums\.slice\(\s*\)\.sort\(\s*\(\s*a\s*,\s*b\s*\)\s*=>\s*a\s*-\s*b\s*\)\s*\s*;?\s*const\s+length\s*=\s*sorted\.length\s*;?\s*const\s+middle\s*=\s*length\s*\/\s*2\s*-\s*1\s*;?\s*return\s+isEven\(\s*length\s*\)\s*\?\s*average\(\s*\[\s*sorted\s*\[\s*middle\s*\]\s*,\s*sorted\s*\[\s*middle\s*\+\s*1\s*\]\s*\]\s*\)/);

If the ternary is false, you should return the value of sorted at the middle index. Use Math.ceil() to round the middle value up.

assert.match(code, /const\s+median\s*=\s*nums\s*=>\s*\{\s*const\s+sorted\s*=\s*nums\.slice\(\s*\)\.sort\(\s*\(\s*a\s*,\s*b\s*\)\s*=>\s*a\s*-\s*b\s*\)\s*\s*;?\s*const\s+length\s*=\s*sorted\.length\s*;?\s*const\s+middle\s*=\s*length\s*\/\s*2\s*-\s*1\s*;?\s*return\s+isEven\(\s*length\s*\)\s*\?\s*average\(\s*\[\s*sorted\s*\[\s*middle\s*\]\s*,\s*sorted\s*\[\s*middle\s*\+\s*1\s*\]\s*\]\s*\)\s*:\s*sorted\s*\[\s*Math\.ceil\(\s*middle\s*\)\s*\]\s*;?/);

--seed--

--seed-contents--

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <link rel="stylesheet" href="./styles.css" />
    <title>Functional Programming Spreadsheet</title>
  </head>
  <body>
    <div id="container">
      <div></div>
    </div>
    <script src="./script.js"></script>
  </body>
</html>

#container {
  display: grid;
  grid-template-columns: 50px repeat(10, 200px);
  grid-template-rows: repeat(11, 30px);
}

.label {
  background-color: lightgray;
  text-align: center;
  vertical-align: middle;
  line-height: 30px;
}

const isEven = num => num % 2 === 0;
const sum = nums => nums.reduce((acc, el) => acc + el, 0);
const average = nums => sum(nums) / nums.length;

--fcc-editable-region--
const median = nums => {
  const sorted = nums.slice().sort((a, b) => a - b);
  const length = sorted.length;
  const middle = length / 2 - 1;

}
--fcc-editable-region--

const range = (start, end) => Array(end - start + 1).fill(start).map((element, index) => element + index);
const charRange = (start, end) => range(start.charCodeAt(0), end.charCodeAt(0)).map(code => String.fromCharCode(code));

window.onload = () => {
  const container = document.getElementById("container");
  const createLabel = (name) => {
    const label = document.createElement("div");
    label.className = "label";
    label.textContent = name;
    container.appendChild(label);
  }
  const letters = charRange("A", "J");
  letters.forEach(createLabel);
  range(1, 99).forEach(number => {
    createLabel(number);
    letters.forEach(letter => {
      const input = document.createElement("input");
      input.type = "text";
      input.id = letter + number;
      input.ariaLabel = letter + number;
      container.appendChild(input);
    })
  })
}