Javascript intruduction 10-24-2012, 04:32 PM
#1
Before you start with Javascript you should know
-Perfect HTML
-CSS
Introduction
Javascript is one of the most popular scripting language in the world it is the programming language of the web for servers, PCs...
Javascript is scripting language a scripting language is a lightweight programming language
Javascript can write directly to HTML output stream react to HTML events and test HTML from input delete and create HTML elements
How to insert javascript in document
There are 3 ways to insert javascript code in document
1.In head tag
Write this in head tagAnd here is example document
Insert in body tag (the same as in head tag but code is write in between body tag)
Write this in the body tagHere is example
Insert from external file
Like in CSS
Write this in body tagand write the scripts in this document
Manipulating HTML elements
You should give to your elements id for example
And use script ot manipulate the element
So your code should look like this
When javascript is executed by the web browser in this case the browser will access the html element (id="demo") and replace its content innetHTML with "My first javascript" or what you have write
Write to the document output
write this code
Use document.write() to write direcly into the document output if you use document.write() after document has finish loading the entire HTML page will be overwritten
Statements
In javascript statements are commands to the browser the purpose of the statements is to tell the browser what to do
Example
This statement tells to the browser to write "Statement" inside an HTML element with id="demo"
!Javascript is case sensitie there is different between function getElementById and getElementbyID or myVariable and MyVariable also javascript ignores extra spaces you can add white space ot your script to make it more readable example :!
Varialbes
variable are containers for storing information
example
In javascript there is only one type variable (not like c++ for example)
example :
and one example about variable
Javascript operators
+ Addition x=2+2
- Subtraction x=5-2
* Multiplication x=3*2
/ Division x=4/2
% Modulus (division remainder) x=5%2 (result for x 1 result for y 5) lets say that y=5
++ Increment x=++y ( result for x 9 result for y 9)lets say that y=5
-- Decrement decrement x=--y (result for =5 result for y =4)lets say that y=5
= x=y
<= x<=y
>= x>=y
+= x+=y same as x=x+y
-= x-=y same as x=x-y
*= x*=y same as x=x*y
/+ x/=y same as x=x/y
%= x%=y same as x=x%y
-Perfect HTML
-CSS
Introduction
Javascript is one of the most popular scripting language in the world it is the programming language of the web for servers, PCs...
Javascript is scripting language a scripting language is a lightweight programming language
Javascript can write directly to HTML output stream react to HTML events and test HTML from input delete and create HTML elements
How to insert javascript in document
There are 3 ways to insert javascript code in document
1.In head tag
Write this in head tag
Code:
<script type="text/javascript"></script>Code:
<html>
<head>
<script type="text/javascript">alert(0);</script>
</head>
<body>
</body>
</html>Insert in body tag (the same as in head tag but code is write in between body tag)
Write this in the body tag
Code:
<script type="text/javascript"></script>Code:
<html>
<head>
</head>
<body>
<script type="text/javascript">alert(0);</script>
</body>
</html>Insert from external file
Like in CSS
Write this in body tag
Code:
<script src="scripts.js"></script>Manipulating HTML elements
You should give to your elements id for example
Code:
<p id="demo">Paragraph</p>And use script ot manipulate the element
Code:
document.getElementById("demo").innerHTML="My first javascript";So your code should look like this
Code:
<p id="demo">Paragraph</p>
<script>
document.getElementById("demo").innerHTML="My first javaScript";
</script>When javascript is executed by the web browser in this case the browser will access the html element (id="demo") and replace its content innetHTML with "My first javascript" or what you have write
Write to the document output
write this code
Code:
document.write("<p> My first paragraph with javascript</p>");Use document.write() to write direcly into the document output if you use document.write() after document has finish loading the entire HTML page will be overwritten
Statements
In javascript statements are commands to the browser the purpose of the statements is to tell the browser what to do
Example
Code:
document.getElementById("demo").innerHTML="Statement";This statement tells to the browser to write "Statement" inside an HTML element with id="demo"
!Javascript is case sensitie there is different between function getElementById and getElementbyID or myVariable and MyVariable also javascript ignores extra spaces you can add white space ot your script to make it more readable example :
Code:
var name ="gagd";
var name = "fsdfs";Varialbes
variable are containers for storing information
example
Code:
var number1 = 1;
var number2 = 2;
var number3 = 3;
var total = number1 + number2 + number4;example :
Code:
var pi = 3.14;
var name = "fname lname";
var c = 'asdad';and one example about variable
Code:
<p id="demo"></p>
var motor="Yamaha";
document.getElementById("demo").innerHTML=motor;Javascript operators
+ Addition x=2+2
- Subtraction x=5-2
* Multiplication x=3*2
/ Division x=4/2
% Modulus (division remainder) x=5%2 (result for x 1 result for y 5) lets say that y=5
++ Increment x=++y ( result for x 9 result for y 9)lets say that y=5
-- Decrement decrement x=--y (result for =5 result for y =4)lets say that y=5
= x=y
<= x<=y
>= x>=y
+= x+=y same as x=x+y
-= x-=y same as x=x-y
*= x*=y same as x=x*y
/+ x/=y same as x=x/y
%= x%=y same as x=x%y





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