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Perform Operations With the Math Object
4:10In addition to the arithmetic operators you learned, JavaScript has a built-in `Math` object used to perform complex mathematical operations on numbers.
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In this stage, you're going to learn how
to create random numbers in JavaScript.
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Applications often need a way to provide
users random choices or outcomes.
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Generating random numbers
comes in handy for
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games or anytime you want to make
your program less predictable.
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For example, in a dice or
card game, each dice roll or
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card shuffle might result in a different
outcome that's randomly generated.
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You create random numbers in JavaScript
using what's called the math object.
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Even though you've already
worked with objects,
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we haven't specifically talked
about what they are just yet.
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So let me teach you some of
the basics of objects first.
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Then we'll dive into the math object and
start generating randomness.
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In JavaScript, data types like strings,
Booleans, and numbers are formally called
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primitive data types, because they're
basic values built into the language.
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A string or number primitive, by itself,
cannot be altered or manipulated.
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It turns out that JavaScript
automatically adds a special wrapper
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around most primitive types so
that you're able to alter them.
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That wrapper is called an object.
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And as you'll learn, JavaScript is
made up of different types of objects.
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In a previous course,
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you learned that even though a string
is just a series of characters inside
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quotation marks, the JavaScript engine
treats it as an object behind the scenes,
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which unlocks useful functionality
by way of properties and methods.
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All objects have properties.
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A property is just like a variable that's
associated with or attached to the object.
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The string object,
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for example, has a property named length,
which holds a numeric value.
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In fact, you've already used the length
property to find the number of characters
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in a string.
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Each defined string has
its own length property,
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because different strings can have
different number of characters in them.
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Objects also have actions
that they can perform.
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We call these actions methods.
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A string, for example,
has the toUpperCase method,
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which you've used before to convert
a string to all uppercase letters.
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There are other types of
objects in JavaScript,
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which you'll learn as you progress
through our JavaScript curriculum.
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For now, I'll introduce you to a special
object called the Math object.
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In addition to the arithmetic operators
you learned, JavaScript has a built-in
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Math object used to perform complex
mathematical operations on numbers.
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For example,
finding the square root of a number or
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working with trigonometric
functions like tangents, sines and
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cosines, which can help you create
more realistic games and animations.
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The MDN or Mozilla Developer Network
provides useful information
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on the properties and
methods of the Math object.
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Here you can see that the Math object
has some properties and many methods.
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The properties are built-in numbers
you can use in certain calculations.
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For example, PI or Math.PI is used
to calculate the area of a circle.
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The methods are mathematical functions
that are built into JavaScript.
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For example, the Math.round
method takes a number like 2.2,
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and rounds it to the nearest whole number,
2 in this case.
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I'll use the JavaScript
console to demonstrate how
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the Math.round method works.
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The math object is a bit unusual in
that you type the word Math with
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a capital M followed by a period and
the method name.
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You will then provide the method a number
value to work with, like 2.2, and
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the method returns a new value,
in this case, 2.
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I'll try another number,
44.9 and see what happens.
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Math.round rounds 44.9 to the nearest
integer and it returns 45.
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The math object is like a built-in library
full of useful mathematical functions.
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As you can see,
there are lots of different methods for
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specific types of math.
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Some are more complex than others.
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For example,
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Math.max returns the largest number from
a set of number values passed into it.
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And Math.acos calculates
the arccosine of a number.
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I have no idea what that is.
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Up next,
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you'll learn how to create a random number
using JavaScript, a really handy skill.
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