JavaScript is
a client side scripting language which gives the functionality of the
application.
JavaScript
code is executed by Web Browser which
is the only language understood by web browsers.
JavaScript is
run by a JavaScript engine which is a part of web browser.
So, the development
environment for JavaScript is Notepad and
the run time environment is Web Browser.
In Notepad, the
scripting code is either written in <head> section or <body>
section.
JavaScript code is inserted within <script>...</script> tags.
Syntax:
<script>
// JavaScript code
</script>
Example:
Creating Variables
JavaScript does not have a concept of typed variables. JavaScript variables are declared by using var keyword.
Syntax: var variable_name;
JavaScript uses object document to traverse html elements. The method getElementById() is used to access elements of html by thier ID.
Example:
Conditional Statements
1. If() statement:
Syntax: if(<condition>)
{
// block of statemnts.
}
2. If...else() statement:
Syntax: if(<condition>)
{
// block of statements.
}
else
{
//block of statements.
}
3. Switch() statement:
Syntax: switch (expression) {
case n:
code block
break;
default:
default code block
}
Looping Statements
1. for() loop:
Syntax: for(initialisation;condition;increment/decrement)
{
//block of statements
}
2. while() loop:
Syntax: while(condition)
{
//block of statements
}
JavaScript Functions
Function is a block of statements which executes whenever called and performs some task.
JavaScript Objects
Example:
Conditional Statements
1. If() statement:
Syntax: if(<condition>)
{
// block of statemnts.
}
2. If...else() statement:
Syntax: if(<condition>)
{
// block of statements.
}
else
{
//block of statements.
}
Syntax: switch (expression) {
case n:
code block
break;
code block
break;
case n:
code block
break;
default:
default code block
}
Looping Statements
1. for() loop:
Syntax: for(initialisation;condition;increment/decrement)
{
//block of statements
}
2. while() loop:
Syntax: while(condition)
{
//block of statements
}
JavaScript Functions
Function is a block of statements which executes whenever called and performs some task.
Function Declaration
JavaScript functions are declared using function keyword.
syntax: function(arguments)
{
// statements
}
Anonymous Functions
The function above is actually an anonymous function (a function without a name).
Functions stored in variables do not need function names. They are always invoked (called) using the variable name.
JavaScript Objects
Objects are
variables which contain variables. Objects are used to store collection of
values.
The values
are stored in name : value pair.
Name represents property and value represents property value.
Syntax: var variable_name = { property1 : “value1”,
property2 : “value2” }
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