There were a lot of changes introduced in the ES6 version of JavaScript in 2015. One of the biggest changes was two new keywords, let
and const
, to create, or declare, variables. Prior to the ES6, programmers could only use the var
keyword to declare variables.
var myName = 'Arya'; console.log(myName); // Output: Arya
Let’s consider the example above:
var
, short for variable, is a JavaScript keyword that creates, or declares, a new variable.myName
is the variable’s name. Capitalizing in this way is a standard convention in JavaScript called camel casing. In camel casing you group words into one, the first word is lowercase, then every word that follows will have its first letter uppercased. (e.g. camelCaseEverything).=
is the assignment operator. It assigns the value ('Arya'
) to the variable (myName
).'Arya'
is the value assigned (=
) to the variablemyName
. You can also say that themyName
variable is initialized with a value of'Arya'
.- After the variable is declared, the string value
'Arya'
is printed to the console by referencing the variable name:console.log(myName)
.
There are a few general rules for naming variables:
- Variable names cannot start with numbers.
- Variable names are case sensitive, so
myName
andmyname
would be different variables. It is bad practice to create two variables that have the same name using different cases. - Variable names cannot be the same as keywords. For a comprehensive list of keywords check out MDN’s keyword documentation.
In the next exercises, we will learn why ES6’s let
and const
are the preferred variable keywords by many programmers. Because there is still a ton of code written prior to ES6, it’s helpful to be familiar with the pre-ES6 var
keyword.
If you want to learn more about var
and the quirks associated with it, check out the MDN var documentation.
Instructions
Declare a variable named favoriteFood
using the var
keyword and assign to it the string 'pizza'
.
Declare a variable named numOfSlices
using the var
keyword and assign to it the number 8
.
Under the numOfSlices
variable, use console.log()
to print the value saved to favoriteFood
.
On the following line, use console.log()
to print the value saved to numOfSlices
.