javacscript:
--------------------
javascript is a scrpting program for useful to develop front end applications,
But recently they were developed node.js so from node.js application javscript
useful as backend application also.
javacsript is implemented in many other application
angular, typescript, reactjs, nodejs, jquery
MOngoDB
javascriptscript is one of concept is developed by brendon eiche 1995.
live script.
java it is Object Oriented Programm and it supports OOPS,
class, object, polymorphism,
javascrit is script based program language or Object based language
. 2015 javascript also introduced some
of the features like
class
object
const
let
array
arrowfunction or lamda expression
var
javascript is implements some features in the year 2015 .
ECMA 2015
(European Computer Manufacturer Association)
ECMA 2015 standard or ES6 standards: Any
javascript is a light weight program,
javascript:
--javscript support operators
--javscripts data typescript
--javascript supports array , Object
--javascript is also control statement
--string
--event handling Mechanism
---validate form
Data types:
------------------------
number
boolean
null
string
javascript also embedded in html
synatx:
OR
Basic Example program to inclue javascript code in Body section HTML:
--------------------------------------------------------------
Example program to include Javscript code in Head Section:
-------------------------------------------------------------------
Operators:
-----------------------------
Operator is a symbol performs action between the operands.
1. Arithmetic
+ 5+2=7
-
*
/
%
2. Assignement Operator:
=
var a=10;
+=
-+
*=
/=
%=
4
3. String Operators:
----------------------
+
var str1="sravan";
var str2="reddy";
var str3=str1+str2;
str3="sravanreddy"
In this example + is an concatenation
4. comparission Operators:OR Relational Operators
----------------------------------
<
>
<=
>=
!=
==
5. Logical Operator:
------------------
&&
||
!
Control Statements in Javscript:
--------------------------------
control statements in java is useful for controlling the flow of execution
conditional
Iterative Or Loop statement
conditional statatements:
if
if-else
elseif
nestedif
switch
loop statement:
for
while
do-while
function in javascript:
----------------------------
Definition: a function is a statements or a group of statement executed by a single unit.
In javascript function definition defined in following ways
syntax:
function function name()
{
statements;
}
Note: function definition in javascript we write either in head section or
in body section.
but function definition execution only possible through function calling
function call: function call in javascript invokes function definition .
syntax:
functionname();
or
using event trigger mechanism to invoke the function definition.
Example program on function using event trigger mechanism:
----------------------------------------------------------
Note: in the above example onclick is an event , similerly
javscript support many event handling mechanisms they are
--> onclick
-->ondblclick
-->onmouseover
-->onmouseout
->onload .....
etc
Example program on function calling:
----------------------------------------------------------
Example program on function with parameters:
--------------------------------------------------
example2:
----------------
Javascript display possibilities:
--------------------------------------------
in javascript to display content we follows the gien ways.
1) Writing into an HTML using innerHTML
2) Writing into an HTMl using document object
3) using window.alert()
4) using console.log()
1. Using InnerHTML:
------------------------
Using innerHTMl
getElement ById method we are using
2)Using document.write()
---------------------------------------------
3)using window.alert()
------------------------------------
4)using console.log()
--------------------------------------------------
Note: in javscript using console object we print the javascript code
on console scree.
in the following example using log method to print text on console screen....
Ways to embedded javscript code in HTML:
------------------------------------------------------------
To embedded script code in html we follows the given ways.
1. body
2. head
3. using external file
3. Using External file:
-------------------------------------------
In javascript using external file to include the code,
in the following examples are included javascript code in external file
Test.js
---------------------------
extern.js
---------------------------------------
function display()
{
window.alert("external js file");
}
Note: In external file inclusion in javascript both file must be
included in the same location.
ECMA2015 OR ES6 standard javascript includes these below features.
let & var keyword:
-------------------------------------------
Ex2:
---------------
Uncaught ReferenceError: i is not defined
at display (Test.html:12)
at Test.html:
Examle program on var keyword:
---------------------------------
Note: The scope of the var keyword exist outside of the method also.
const keyword:
-----------------------------------------
ex2:
---------------
Uncaught SyntaxError: Missing initializer in const declaration
Arrow function :
-------------------------------------------
Arrow function in javascrit follows with a different syntax:
equal sign before of the parenthesis and after paraenthesis arrow sign
Arros function concept executed by fast by the engine.
this keyword:
----------------------------------------
here this is a keyword, in javascrit this keyword referes
to the global object by default i.e
it referes window object
object contais(properties and methods)
output: window
window object
Declare this keyword in normal function:
---------------------------------------------
return: global object i.e window
Example program on this keyword declared in Object:
-------------------------------------------------------
whenever we declare this keyword inside of any
object in that case this keyword return only that object
related data only.
javascript objects:
-------------------------------------------------
A javascript object is an entity has state and it's behaviour
(properties and methods)
--> it is not a class based language .
In java how we create Object:
first we create class
after that we create object
In javascript class doesn't exist
we create directly Object
Note: we don't create any class, but we will create object directly.
How many ways we create Object in javascript:
--------------------------------------------
Here in javascript object creattion is mainly follows in 3 ways.
1) By using Object literals
2) By using instance of an Object
3) By using Object constructor
1. By using Object Literals:
-----------------------------------
In javascript object literal follows the given syntx:
Object ={Property1: value1,property2:value2................}
2) By Using Object Instance:
-----------------------------------------
syntax:
var objectname=new Object();
3) By using Object constructor:
----------------------------------------------
Builtin methof of an Object:
-----------------------------------
1. assign()
2.is()
3. freeze()
4.isfrozen()
Example program on Object.assign() method:
---------------------------------------------------
Example program on is() emthod in javascript:
----------------------------------------------------------
Object.is() method used to determine whether two values
are same values or not.
Object.is() method in javascript
Example program on freeze();
--------------------------------------------
when we apply freeze( ) method for any perticular object
then taht object values doesn't modify or updated.
Example program on isfrozen();
-----------------------------------
Using isfrozen() method we check the objects which are in freeze state or not
javascrit Date:
------------------------------------------
javascript date object exist with multiple
builtin methods. using those methods we find the
date, year ,month etc....
Date object built-in methods:
-----------------------------
getDay()
getFullYear()
getHours()
getMilliSeconds()
getMinutes()
Array Object in javscript:
---------------------------------------------------
in javascript Array is an Object represetns collection of
similer type of elements.
Array Object in javascript created mainly in 3 ways:
------------------------------------------------
Those are
1. By array literal
2. By crating an instance of an array
3. by using array constructor
1. By Array Literals :
---------------------------------------
var arrayobject=[valu1,value2,...........]
2. By creating an instance of an array:
----------------------------------------------
3.using Array constructor
----------------------------
Array Methods in javacsript:
-------------------------------------
The following builtin methods supported by javascript.
1. concat()
2. filter()
3. reverse()
4. sort()
1.
2.
3. revers()
4.
Browser related Objects:
----------------------------------
1. window
2. history
3. screen
1. window:
----------------------
alert()
confirm()
prompt()
open()
open();
----------------
2. History Object:
------------------------------
forward()
go()
FormValidation:
------------------------------