Arrays are used to store multiple values in a single variable.

Each value is called an element, and each element has a numeric position in the array, known as its index.

Arrays are zero-indexed, meaning the first element is at index 0, the second at index 1, and so on.

Arrays can contain any data type, including numbers, strings, and objects.

const arr1 = [2, 4, 6]; array

arr1[0]; element at index 0 → 2

arr1[1]; element at index 1 → 4

arr1[2]; element at index 2 → 6

arr1[3]; element at index 3 → undefined index not found

---

Numbers are used to represent both integer and floating-point values.

Numbers are most commonly expressed in literal forms like 255 or 3.14159 ↴

let num1 = 5; → number

let num2 = 2.5; → number

let num3 = num1 + num2;

console.log(num3); returns ↴

7.5 → number

---

Find the maximum difference between two numbers in an array using a for loop

---

for loop repeatedly executes a block of code until a specified condition evaluates to false.

The loop runs a block of code a set number of times, defined by an initialization, a condition, and an increment.

for (let x = 0; x < 4; x++) {

console.log(x);

}

Loop variable x is initialized to 0

Condition x < 4 is checked before each iteration.

The loop will continue to run as long as x is less than 4

The loop repeatedly executes a block of code 4 times, from 0 to 3

For each iteration of the loop, the current value of x is printed to the console.

After each iteration, x is incremented by 1 x++

When x reaches 4 the condition evaluates to false, terminating the loop.

0

1

2

3 → printed to console

---

Initialize a variable to hold the array find the maximum difference between two numbers.

const array1 = [4, 8, 6, 2, 5, 7, 9, 3]; → user input

---

Define a function maxDifference to find the maximum difference between two numbers.

function maxDifference(arr) {}

The function takes an array as input arr and returns the maximum number between two numbers found in the array.

If the array has less than two elements, return 0 and end execution of function.

if (arr.length < 2) return 0

If the array has two or more elements, initialize min and max values to the first element of the array.

let minVal = arr[0] minVal

let maxVal = arr[0] maxVal

Iterate through the array starting from the second element.

for (let x = 1; x < arr.length; x++) {

Check if the current element arr[x] is smaller than minVal

if (arr[x] < minVal) {

If true, update minVal with current value.

minVal = arr[x]

Check if the current element arr[x] is larger than maxVal

if (arr[x] > maxVal) {

If true, update maxVal with current value.

maxVal = arr[x]

Return the difference between maxVal and minVal

return maxVal - minVal

---

Call the function with ↴

maxDifference(array1);

---

Find the maximum difference between two numbers in an array.

arr = [4, 8, 6, 2, 5, 7, 9, 3]

minVal = arr[0] → 4

maxVal = arr[0] → 4

Loop through the array starting from the second element.

for (let x = 1; x < arr.length; x++)

Update minVal if the current element is smaller.

if (arr[x] < minVal) {

minVal = arr[x];

}

Update maxVal if the current element is larger.

if (arr[x] > maxVal) {

maxVal = arr[x];

}

minVal = 2

maxVal = 9

maxVal - minVal;

9 - 2 → 7 maximum difference between two numbers in an array

---

Find the maximum difference between two numbers in an array.