JavaScript variables

Variables store values (data) to make the data more compact and portable for different parts of a JavaScript program. Instead of using the data as-is, we can store them in variables and call them by their variable names. They are like the "pronouns" of programming languages.

JavaScript statements take on a form similar to a mathematical equation (a variable gets a value), but in a manner similar to an assignment (see the second line):

let x = 2
x = x + 1 // 3

In the example above, we do not mean that x is equal to x+1 (which makes no sense) but that:

"x will have a value of the last known value of x (i.e. 2); x will then add 1 to itself to make 3!"

Alternatively, we can think of the single = sign as a left-facing arrow:

x <- 2
x <- x + 1

"let x be 2, then let x be 2 + 1"

If only we could rewrite the programming language!