Learning JavaScript made easy

                                        JAVA Script

JavaScript is a programming language of Html and its a scripting language. JavaScript doesn’t compile meaning it doesn’t translate to other languages before executing.It transpile.

JavaScript is language that function from the front end. It is non blocking meaning it doesn’t refresh.

                                       Variables (JavaScript)

In JavaScript, a variable contains a value, such as "hello" . When you use the variable, you refer to the data it represents.

e.g    var room =26;

          var name = “Stanley”

You use variables to store, retrieve, and manipulate values that appear in your code. Try to give your variables meaningful names to make it easy for other people to understand what your code does.

                                        Declaring Variables

The first time a variable appears in your script is its declaration. So you can refer to it later on in your script. You should declare variables before using them. You do this using Var keyword; see the example above.

                         Naming Variables

·        Do not give your variable a key word .

·        Variable must not contain spaces.

·        Can not start with  numbers but can end with numbers

          Eg   var 23long   ------à this is wrong

                      var long23  -------à this is correct.

·        Variable are case-sensitive.

·        You can use a dash or underscore  ( - or _ )at the beginning or at the middle of a variable.

       Eg             var  sta_nlo

                         var  _stanlo

·        You can name a variable using camelcase.

        Eg             var  firstName

Variables should not start with a Cpital letter but use camelcase instead.

                               VARIABLE DATA TYPES

1.     Number Data Type: this is divided into 2

Ø integer values

Ø floating-point values

                                            Integer Values

Integer values can be positive whole numbers, negative whole numbers, and 0. They can be represented in base 10 (decimal), base 16 (hexadecimal), and base 8 (octal). Most numbers in JavaScript are written in decimal.

                               Floating-point Values

Floating-point values can be whole numbers with a decimal portion. Additionally, they can be expressed in scientific notation. That is, an uppercase or lowercase "e" is used to represent "ten to the power of".

 A number that contains a decimal point and that has a single "0" before the decimal point is interpreted as a decimal floating-point number.

                                     String Data Type

You use the string data type to represent text in JavaScript. You include string literals in your scripts by enclosing them in single or double quotation marks. Double quotation marks can be contained in strings surrounded by single quotation marks, and single quotation marks can be contained in strings surrounded by double quotation marks. The following are examples of strings:

eg

"Happy am I; from care I'm free!" 

'"Atlast, I’m free!" roared the technician.'  

"45" 

'c'

         

                                         Boolean Data Type

Whereas the string and number data types can have a virtually unlimited number of different values, the Boolean data type can only have two. They are the literals true and false. A Boolean value is a truth-value: it specifies whether the condition is true or not.

                               JavaScript Operators

·         +     :addition

·         _     :subtraction

·         X    :multiplication

·         /      :division

·         <     :less than

·         >     :greater than

·         %  ( modulo):
                    This is used to check if a number is even [ this always get the remainder in calculation]   e.g 10%5= 0

·         <=   :less or equal to

·         >=    :greater or equal to

·         =   : this is used to assign a value from the right to your left

·         ==   :this mean equal to

·         ===   :this mean you tell computer to check if they are of the same type  (compare).

·         !=    :not equal.

·         !==   :not equal value or not equal type

                              Conditional Statements

These are statements used to perform different actions for different decisions.

They are as follow

IF Statement

ELSE Statement

ELSE IF  Statement