Arrays

- Regular variables are great for storing numbers, strings, and other single items. But what do you do if you have several related items and you want to store them all at the same time like a list of things. For that we have a special type of variable called an array. The array is one of the cornerstones of Java script programming and moving forward you'll see me use arrays in many different ways for different purposes. An array is literally an array where you can store as few or as many items as you like and retrieve one of, some of, or all of those items.

To create an array first create an undefined variable so var pens. Then add the different values to the array using a comma separated list wrapped in square brackets so something like pens equals red, blue, green, orange. This is a shorthand for the full command pens equals new array red, blue, green, orange which produces the exact same array.

This long hand tells us an array is an object which we'll talk more about later. One interesting note about arrays each value in the array can be a separate data type so you can mix strings, Booleans, and numbers all you like. Var mixed bag equals the string keys, the number five, the Boolean false, the number 568, and the string one more thing. You can also add arrays within arrays so called multidimensional arrays but that's beyond the scope of our current conversation.

Each of the values added to an array is placed in a separate slot and given an index number. Computer indexes start with zero so the first item has index number zero, the second the number one, and so on. Once the array is created, you can retrieve a specific value from the array based on its index so if you want the value number four in the array you call for fourth pen equals pens and then square brackets three. If you need to change a value in the array you simply refer to its index position and assign a new value.

Pens square brackets three equals purple.