Arrays Study Guide

What are Arrays?

An array is a data structure that stores a collection of elements, each identified by at least one array index or key. It is a way to store multiple values in a single variable.

Declaring and Initializing Arrays

To declare and initialize an array in JavaScript, you can use the following syntax:

    
      var fruits = ["apple", "banana", "orange"];
    
  

This creates an array called fruits with three elements: "apple", "banana", and "orange".

Accessing Array Elements

You can access individual elements in an array using their index. Array indices start at 0, so the first element is at index 0, the second element is at index 1, and so on. For example:

    
      var firstFruit = fruits[0]; // Accesses the first element ("apple")
      var secondFruit = fruits[1]; // Accesses the second element ("banana")
    
  

Array Methods

Arrays come with built-in methods for performing various operations, such as adding or removing elements, sorting, and looping through the array. Some commonly used array methods include:

• push() - Adds one or more elements to the end of an array
• pop() - Removes the last element from an array
• splice() - Adds or removes elements from an array
• forEach() - Executes a provided function once for each array element

Multi-Dimensional Arrays

An array can also contain other arrays, creating a multi-dimensional array. This is useful for storing and working with more complex data structures, such as matrices or tables.

    
      var matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];
    
  

Conclusion

Arrays are a fundamental concept in programming and are used to store and manipulate collections of data. Understanding how to work with arrays is essential for any programmer.

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