variables.md

Variables

Below is a list of all JavaScript variable types. JavaScript is "loosly" or "weakly" typed, which means that variable types do not need to be explicitly declaired. Where in some languages you need to declare a variable like:

int myInt = 5;
// or...
string myString = "Hello World";

In JavaScript you simply use the var keyword:

var myInt = 5;
// or...
var myString = "Hello World";

In JavaScript there are 8 variable types:

1. Boolean
2. Int
3. Float
4. Char
5. String
6. Array (and Associative Array)
7. Object
8. Function

Boolean

Booleans variables can be true or false only.

var myBoolean = true;

Int

Int variables are whole numbers.

var myInt = 5;

Float

Float variables are numbers with decimal points (also called floating-point numbers).

var myFloat = 5.5;

Char

Chars are single characters. They can represent text, a number, or even unicode characters.

var myChar = 's';

Note that a '5' is different than a 5.

String

Strings are combined characters, they hold things like words or sentences.

var myString = 'string';

Array

An array is a list of variables of any type. Arrays can hold booleans, ints, floats, chars, strings, objects, functions (don't do this), and even other arrays. Arrays can also hold variables of different types. i.e. strings and ints. Although this is considered bad practice and can lead to some hard-to-find bugs

var myIntArray = [5, 10, 12, 14, 800];
var myStringArray = [
					 "Ulysses",
					 "The Great Gatsby",
					 "1984",
					 "Catcher in the Rye",
					 "A Clockwork Orange"
					];

Each value in an array is called an element. Elements can be accessed using the "index", or position in the array, where that value is located. Array indexes start at 0 instead of 1.

// returns "Ulysses"
myStringArray[0];

// returns "A Catcher in the Rye"
myStringArray[3];

//etc...

Associative Arrays store values with a string index instead of a numerical one. This is helpful for storing data with human-readable keys. For instance, storing id numbers in an array with each index being the student's last name.

var myAssocArray = [];
myAssocArray['Thompson'] = 345;
myAssocArray['Johnson'] = 487;
myAssocArray['Wallace'] = 101;

// returns 345
myAssocArray['Thompson'];

// returns 101
myAssocArray['Wallace'];

//etc...

##Object

An object is a special kind of data, with properties and methods. Properties are kind of like variables that belong to an object and methods are like functions that belong to an object.

var myObject = {
	property: "value";
	method: function(){
		// some code...
	}
};

Objects can be created all at once like this...

var myCar = {

	make: "Subaru",
	model: "Legacy",
	type: "Station Wagon",
	year: 1992,
	color: "champagne",
	offRoad: false,
	drive: function(){
		// code to drive
	},
	doCoolTrick: function(){
		// code to look like a badass
	}
};

or separately like this...

var myCar = {};
myCar.make = "Subaru";
myCar.model = "Legacy";
myCar.year = 1992;
// etc...

An object's properties and methods are accessed using "dot syntax" just like we assigned them above

// returns "Subaru"
myCar.make;

// runs the code for that badass trick
myCar.doCoolTrick();

Function

In JavaScript, functions are actually variables. This can be confusing, but also very helpful.

var myFunction = function(parameter1, parameter2, etc...){
	// code...
}

// run the function
myFunction();

Cool, thats all of them. There are some programming books that are entirely devoted to variable types, so if all of this doesn't make since just yet don't sweat it. The nice thing to know is that you just learned every variable type in JavaScript!