2 . 2 - Variables 

Review

Web browsers can run a scripting language called JavaScript. The syntax is very similar to C, C++, C#, Java, etc...

Last class we learned about something called the console.

• The JavaScript console provides printed output to the developer (that's you!).

  • on a website, the user normally does not see the console but they can - so be careful what you put there.

• We can print to the console with console.log(); 

  • For example:  console.log("This is a string of text")

• There are special "escape characters" for new lines (\n), tabs (\t), slash (\\), and more.

Synopsis:

Variables hold data in the memory of the computer.

let w = 2;

let apples = 7;

let myList = w + apples;  // sets the variable 'myList' to 9

console.log(myList);      // output the value of 'myList'

Note - you might see the keyword var being used online instead of let. You should always use let when creating a variable. I will essentially assume you cheated if I see var in your code.

Variables can be modified and reused:

When modifying the value of a variable you do not need to use the let keyword again - the variable already exists!

let age = 7;

age = 25;

age = age + 1;

Variables can be different types of data:

let my_number = -45;
let my_string = "Some text, in quotes";
let my_boolean = true;   // or false

Strings

• Can be combined (concatenated) using the '+' operator
  my_string = "This " + "that";   //  the value is now 'This that'

• Strings cannot be subtracted
  my_string = "This that" - "that";   //  not possible

Booleans

• Anything with value is considered 'true'
  let sample1 = 5;  // considered true
  let sample2 = 0;  // considered false
  let sample3;      // considered false