Learn Functional Programming by Building a Spreadsheet - Step 22

Tell us what’s happening:

I’m not sure if I’m just being dumb or anything but I’m having a hard time understanding these specific instructions: “sorting a copy of the `nums` array.” I don’t know how exactly to sort it in the way it’s telling me to.

``````<!-- file: index.html -->
<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<body>
<div id="container">
<div></div>
</div>
<script src="./script.js"></script>
</body>
</html>
``````
``````/* file: styles.css */
#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;
}
``````
``````/* file: script.js */
const isEven = num => num % 2 === 0;
const sum = nums => nums.reduce((acc, el) => acc + el, 0);
const average = nums => sum(nums) / nums.length;

// User Editable Region

const median = (nums) => {
const sorted = nums.slice().sort(() => );
}

// User 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));

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);
})
})
}
``````

User Agent is: `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 OPR/106.0.0.0`

Challenge Information:

Learn Functional Programming by Building a Spreadsheet - Step 22

Hi there. The sort method needs to receive a callback function with two variables. Like other callback functions made so far , two parameters are defined in parentheses and an operation is performed with these two parameters to determine the order.

Traditionally these two variables are called `a` and `b` because they represent the first and second number. The first element is deemed smaller by returning a negative number; the first element is deemed bigger by returning a positive number. If it returns zero, then the two are equal.

Hope this helps.

P.S More on the sort callback.

Hi, although I have not came to your level, I would like to say something about my understanding, for “sorting a copy of the `nums` array.”, is the meaning that using a copy of array? if so, I think it should be using like this […nums].

The word “sorting” is where I’m confused at. I already know how to make a copy of an array and that’s by using the `slice()` method.