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Introduction to JavaScript

# Libraries

Instance methods, by definition, require that you create an instance before you can use them. What if you want to call a method without an instance? That's where JavaScript libraries come in. Libraries contain methods that you can call without creating an instance.

One such collection contains mathematical methods, aptly named the `Math` library.

Let's see how you call the `.random()` method from the `Math` library:

``````console.log(Math.random()); // random number between 0 and 1
``````

In the example above, we called the `.random()` method by appending the library name with a period, the name of the method, and opening (`(`) and closing (`)`) parentheses. This method returns a random number between 0 and 1. This code prints a random number between 0 and 1.

To generate a random number between 0 and 50, we could multiply this result by 50, like so:

``````Math.random() * 50;
``````

The answer in the example above will most likely be a decimal. To ensure the answer is a whole number, JavaScript provides a built-in method called `Math.floor()`. `Math.floor()` takes a decimal number, and rounds down to the nearest whole number. You can use `Math.floor()` to round a random number like this:

``````Math.floor(Math.random() * 50);
``````

In this case:

1. `Math.random` generates a random number between 0 and 1.
2. We then multiply that number by `50`, so now we have a number between 0 and 50.
3. Then, `Math.floor` rounds the number down to the nearest whole number.
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