added all tests to test, started mean.js but not finished

Author: asaniDev

prep/mean.js

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+//a data structure is used to group data together. it is a collection of data which has functions which allow you to access and manipulate the data.
+//an array is a zero indexed collection of data that holds data in an ordered list.
+function calculateMean(list) {
+  let total = 0;
+
+  for (const item of list) {
+    total += item;
+  }
+}
+
+function calculateMedian(list) {
+  const middleIndex = Math.floor(list.length / 2);
+  const median = list.splice(middleIndex, 1)[0];
+
+  return median;
+}
+
+calculateMean([10, 20, 30, 40, 50]);

prep/mean.test.js

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+test("calculates the mean of a list of numbers", () => {
+  const list = [3, 50, 7];
+  const currentOutput = calculateMean(list);
+  const targetOutput = 20;
+
+  expect(currentOutput).toEqual(targetOutput);
+});
+
+test("calculates the median of a list of odd length", () => {
+  const list = [10, 20, 30, 50, 60];
+  const currentOutput = calculateMedian(list);
+  const targetOutput = 30;
+
+  expect(currentOutput).toEqual(targetOutput);
+});
+
+test("doesn't modify the input", () => {
+  const list = [1, 2, 3];
+  calculateMedian(list);
+
+  expect(list).toEqual([1, 2, 3]); // Note that the toEqual matcher checks the values inside arrays when comparing them - it doesn't use `===` on the arrays, we know that would always evaluate to false.
+});

prep/package.json

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+{
+  "name": "prep",
+  "version": "1.0.0",
+  "description": "",
+  "main": "mean.js",
+  "scripts": {
+    "test": "jest"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "type": "commonjs",
+  "devDependencies": {
+    "jest": "^30.2.0"
+  }
+}