Array Overview

What are arrays?

• A collection of objects or items
• “Zero-based” - positions (called indexes) start at zero
• Very easy way to store multiple items
• Arrays can hold items of different datatypes (i.e. all items in an arry don’t have to be the same datatype)
• Used extensively in programming

Declaring an array

Two ways to declare an array

// Declaring an empty array using the Array constructor syntax
var names = new Array();

// Declaring an empty array using literal notation (preferred)
var names = [];

// Declaring an array using literal notation with data
var names = ['larry', 'curly', 'moe'];

Arrays and Indexes

Arrays are “zero-based” meaning indexes start at 0

  // the value 'curly' is said to have an index of 1
  var names = ['larry', 'curly', 'moe'];

Getting data out of an array

The most common way to retrieve a single value from an array is to use the index

  var names = ['larry', 'curly', 'moe'];

  // retrieve the first item out of the array
  names[0]; // this wil return 'larry'

More information about arrays

• Arrays one of the most useful data structures in programming, check our MDN’s documentation on Arrays for more information