Javascript-Lesson 2
Case, Comments and Blocks
Case
Javascript is case-sensitive. Be very careful where and when you use capital letters.
Comments in Javascript
A single line comment is started with a double forward slash. E.G //This is a comment. This type of comment can also be used to follow a javascript statement.
A longer comment is contained in the same characters as CSS comments. E.G./*This is a much longer Javascript comment.*/
Blocks
Each group of self-contained Javascript statements (block)should be contained in curly brackets.
Javascript Variables
Variable
Variables in Javascript contain values. Such values can be numbers or even text. Variables are also of two types, 'local' and 'global'. Local variables are those whose use is restricted to a particular portion of the script. Global variables can be used anywhere in the script.
Variable Names
Variable names are also case sensitive. They can be can contain any combination of letters, digits or underscores, '_'. They can be long and descriptive (e.g. price_of_oranges) or short (e.g. x, y or z). They must start with a letter or an 'underscore'
| abstract as boolean break byte case catch char class |
continue const debugger default delete do double else enum |
export extends false final finally float for function goto |
if implements import in instanceof int interface is long |
namespace native new null package private protected public return |
short static super switch synchronized this throw throws transient |
true try typeof use var void volatile while with |
Variable names must not be one of Javascript's reserved words. I.E. words that have a specific meaning in Javascript.
Declaring a Variable
var variable_name; //What the variable is!
This is the way to 'declare' a variable. It is not obligatory to declare variables, but it makes sense to do so.
Assigning a Variable
x = 3;
is an example of assigning a variable. However a variable declaration can be combined with its assignation. e.g.
var x = 3; // x is the number of apples
