Mastering JavaScript Arrays Sum-Up

Arrays are data structures used to store and manipulate collections of values.

Creating Arrays

• Arrays in JavaScript are created using square brackets [] and are known as array literals;

• Commas separate elements within the array.

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// Array literal creation
const colors = ["red", "green", "blue"];
const numbers = [1, 2, 3, 4, 5];

// Arrays with different data types
const mixedArray = ["apple", 42, true, { name: "John" }];

Accessing Array Elements

• Array indices start at 0, meaning the first element has an index of 0, the second element has an index of 1, and so on;

• Specific elements within an array can be accessed by using square brackets with the element's index.

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const firstColor = colors[0]; // "red"
const secondNumber = numbers[1]; // 2

Modifying Array Elements

Array elements can be changed by accessing them through their index and assigning a new value.

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colors[1] = "yellow";
numbers[0] = 10;

Array Length

The length property of an array represents the number of elements it contains. It automatically adjusts when elements are added or removed.

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const colorsCount = colors.length; // 3
const numbersCount = numbers.length; // 5

Finding the Last Element

To retrieve the value of the last element in an array, we can calculate its index using the array's length, which is array.length - 1.

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const lastColor = colors[colors.length - 1];
const lastNumber = numbers[numbers.length - 1];

For Loop

• The for loop is used for iterating over an array element by element;

• It uses a loop counter variable (e.g., i) to access each element by index;

• The loop continues as long as the counter is less than the array's length;

• It's a fundamental tool for array iteration.

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for (let i = 0; i < numbers.length; i+=1) {
  console.log(numbers[i]);
}

For...of Loop

• The for...of loop is a more modern and concise way to iterate over arrays;

• It automatically handles the loop counter and provides direct access to each element's value;

• It simplifies array iteration, making the code cleaner and more readable.

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for (const color of colors) {
  console.log(color);
}