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Arrays are one of the most useful data types you have as a JavaScript developer.

Arrays are the best way to group similar data together in a sequence,

such as a list of customers, photos, dates, or

even coordinates indicating a precise spot on a screen.

To use arrays effectively,

you need a way of looking through them to see the data they hold.

This action of looking through arrays is called iteration, and

JavaScript provides many methods for iterating over an array.

For example, you might wanna transform an array's elements, say,

from strings to numbers.

Or you might want to add an array of numbers and return the sum.

Maybe you have an array of dates and

you want to remove all dates before, say, July 1st.

In this course,

I'll show you how to use array methods to accomplish these kinds of tasks.

You'll also practice iterating over arrays so

you can retain the knowledge you'll build here.

Before diving in though, let's take a moment to review what arrays are.

An array is a sequenced selection of data, basically a list of information.

In fact, arrays are sometimes referred to as list like objects in JavaScript.

Think of a list on a piece of paper, like a shopping list for example.

A shopping list is a group of items you need to buy.

Those items appear in specific order, starting at the top and going down.

So when you want to add something to the list, you write it at the bottom.

JavaScript arrays have similar characteristics.

You can store and position data inside them as you can with a list.

To add data to an array, you typically write it in using a push method for

example.

Storing anything whether it is a name on a list or

an item in an array is useless unless you can find it again later.

To find a list item, you'll typically start reading at the top and

go down till you see what you're after.

You can look through arrays in a similar manner, but with arrays,

this process is called iteration.

And unlike a shopping list,

which is really a collection of strings, the names of each item you want to buy,

you can store any JavaScript data type as an item in an array.

A string, a number, an object, and even another array.

JavaScript uses integers called indices to identify the position

of an item in an array.

The first item in an array is that index 0, the next item is at 1 and so on.

This means if you know the location of an item in an array,

you can access it directly with its index.

Put the index and

square brackets after the array to access a specific piece of data.

In the next video, we'll compare two way to iterate over an array.

A for loop, and an array method called for each, I'll see you there.