Built-in Objects

In addition to console, there are other objects built into JavaScript. Down the line, you’ll build your own objects, but for now these “built-in” objects are full of useful functionality.

For example, if you wanted to perform more complex mathematical operations than arithmetic, JavaScript has the built-in Math object.

The great thing about objects is that they have methods! Let’s call the .random() method from the built-in Math object:

In the example above, we called the .random() method by appending the object name with the dot operator, the name of the method, and opening and closing parentheses. This method returns a random number between 0 (inclusive) and 1 (exclusive).

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

The example above will likely evaluate to a decimal. To ensure the answer is a whole number, we can take advantage of another useful Math 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 down a random number like this:

In this case:

• Math.random() generates a random number between 0 and 1.

• We then multiply that number by 50, so now we have a number between 0 and 50.

• Then, Math.floor() rounds the number down to the nearest whole number.

If you wanted to see the number printed to the terminal, you would still need to use a console.log() statement:

To see all of the properties and methods on the Math object, take a look at the documentation here.

Instructions

1.Inside of a console.log(), create a random number with Math.random(), then multiply it by 100.

2.Now, use Math.floor() to make the output a whole number.

Inside the console.log() you wrote in the last step, put the existing Math.random() * 100 code inside the parentheses of Math.floor().

3.Find a method on the JavaScript Math object that returns the smallest integer greater than or equal to a decimal number.

Use this method with the number 43.8. Log the answer to the console.

4.Use the JavaScript documentation to find a method on the built-in Number object that checks if a number is an integer.

Put the number 2017 in the parentheses of the method and use console.log() to print the result.