Client-side vs. Server-side

 24 Aug Admin

o     The World Wide Web is built on a number of different technologies.

o     For most users, the web starts and ends with their choice of web browser. The browser is said to define the client-sideof the web, with the browser, the computer it is running on, and the user surfing the web being collectively referred to as the client.

o     Consider a client who has decided to visit the web site at www.google.com. The first thing that happens is that the client will make a request to Google’s web server for the default page of that web site.

o     The web server is an application running on a computer owned by Google. Like the client, the server application and the computer on which it runs define the server-side of the web, and are collectively referred to as the server.

o     When the server receives the request from the client for a particular page, its job is to retrieve the page from the computer’s files and serve it back to the client. In many cases, this operation is a very simple procedure involving little or no work on the part of the server.

o     However, using a programming language like PHP, Perl or Java, we can cause the server to either modify the page it finds before it passes it back to the client, or even to generate the page entirely from scratch. This is referred to as a server-side application. The page passed back to the client looks (to the client) exactly the same as any other page that has not been modified.

o     An example of a server-side application might be to insert the current date and time into a page. This would mean that each time the page was requested (say, by using the browser’s refresh button), a new time value would be added to the page.

o     Once the client has received the page from the server, it displays the page and waits for the user to request another page. As soon as the page reaches this state, it has moved beyond the control of the server. No server-side application can now alter the contents of the page without the client having to make another trip back to the server to get a new (and possibly updated) copy of the page.

o      However, all modern browsers allow for the running of clientside applications. These are small applications which are embedded within the HTML code of the page itself.

o     Server-side applications ignore any client-side applications that they find while modifying pages to send to the client, so in general the two types of application cannot easily “talk” to each other.

o     However, once the client has received a client-side application, it can begin to modify the page dynamically, without the need to go back to the server.

o     An example of a client-side application might be a clock on a web page that updated every second.

o     An unfortunate side effect of client-side applications is that all the code must be sent to the client for running, which means that the application’s inner workings are available for anyone to see. This makes it impractical for checking passwords, or doing anything else that could cause confidential information to be released into the wild.

o     In addition, all modern web browsers afford the user the opportunity to switch off client-side applications altogether. On top of this, the way the same client-side application is run will vary from browser type to browser type.

o     Despite these drawbacks, client-side applications (or scripts, as they are better known due to their general brevity) remain the best way to provide web users with a rich environment when developing web applications.

o     In short, the two technologies each have their strengths and weaknesses:

o     Client-side scripts allow the developer to alter pages dynamically, and to respond to user actions immediately rather than having to wait for the server to create a new version of the page. However, there are security and cross-browser compatibility issues to be aware of, and these are often nontrivial.

o     Server-side applications allow the developer to keep her code secure and secret, thus allowing for more powerful applications to be created. In addition, since the server running the code is always a known quantity, applications that run successfully in one browser will run successfully in all browsers. However, despite all this power, there is no direct way for a server-side application to alter a page without having to force the client-side to load another page. This makes it completely impractical for things like drop-down menus, pre-submission form checking, timers, warning alerts and so forth.

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Implementation

24 Aug  Admin

Implementation in JavaScript can be done in following two ways :-

1. Internal JavaScript

2. External JavaScript

Internal JavaScript

In internal javaScript , Javascript code is implemented internally inside the head section or inside the body section.

Inside the head section

24 Aug  Admin

Implementation in JavaScript can be done in following two ways :-

1. Internal JavaScript

2. External JavaScript

Internal JavaScript

In internal javaScript , Javascript code is implemented internally inside the head section or inside the body section.

Inside the head section

Inside the body section                      

Inside the body section                      

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Introduction to JavaScript

24 Aug   Admin

JavaScript is a client side programming language used to add programming logic to web pages.

Brendan Eich (born July 4, 1961) is an American technologist and creator of the JavaScript programming language. He co-founded the Mozilla project,[2] the Mozilla Foundation and the Mozilla Corporation, and served as the Mozilla Corporation’s chief technical officer and briefly, as its chief executive officer.[3] He is the CEO of Brave Software.[4] For more(Wikipedia.org)

Applications of JavaScript :-

  • Client side valiadtion
  • Helps in manipulating HTML pages
  • User Notification (Pop-ups in website)
  • Back-end Data Loading (Ajax library)
  • Presentations (RevealJs and BespokeJs)
  • Server Applications (NodeJs)

There are many useful Javascript libraries available:-

  • Angular
  • React
  • jQuery
  • Vue.js
  • Ext.js
  • Ember.js
  • Meteor
  • Mithril
  • Node.js
  • Polymer
  • Aurelia
  • Backbone.js etc.

Basic JavaScript Example :-

<html>

         <body>

                <script>

                </script>

         </body>

</html>

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Operators

C operators are symbols that are used to perform mathematical or logical manipulations. The C programming language is rich with built-in operators. Operators take part in a program for manipulating data and variables and form a part of the mathematical or logical expressions.

Types of operators:-

C programming language offers various types of operators having different functioning capabilities.

  1. Arithmetic Operators
  2. Relational Operators
  3. Logical Operators
  4. Assignment Operators
  5. Increment and Decrement Operators
  6. Conditional Operator
  7. Bitwise Operators
  8. Special Operators

Arithmetic Operators:-

C supports all the basic arithmetic operators. The following table shows all the basic arithmetic operators.

OperatorDescription
+adds two operands
subtract second operands from first
*multiply two operand
/divide numerator by denominator
%remainder of division
++Increment operator – increases integer value by one
Decrement operator – decreases integer value by one

Relational operators:-

The following table shows all relation operators supported by C.

OperatorDescription
==Check if two operand are equal
!=Check if two operand are not equal.
>Check if operand on the left is greater than operand on the right
<Check operand on the left is smaller than right operand
>=check left operand is greater than or equal to right operand
<=Check if operand on left is smaller than or equal to right operand

Logical operators:-

C language supports following 3 logical operators. Suppose a = 1 and b = 0,

OperatorDescriptionExample
&&Logical AND(a && b) is false
||Logical OR(a || b) is true
!Logical NOT(!a) is false

Bitwise operators:-

Bitwise operators perform manipulations of data at bit level. These operators also perform shifting of bits from right to left. Bitwise operators are not applied to float or double(These are datatypes, we will learn about them in the next tutorial).

OperatorDescription
&Bitwise AND
|Bitwise OR
^Bitwise exclusive OR
<<left shift
>>right shift

Assignment Operators:-

Assignment operators supported by C language are as follows.

OperatorDescriptionExample
=assigns values from right side operands to left side operanda=b
+=adds right operand to the left operand and assign the result to lefta+=b is same as a=a+b
-=subtracts right operand from the left operand and assign the result to left operanda-=b is same as a=a-b
*=mutiply left operand with the right operand and assign the result to left operanda*=b is same as a=a*b
/=divides left operand with the right operand and assign the result to left operanda/=b is same as a=a/b
%=calculate modulus using two operands and assign the result to left operanda%=b is same as a=a%b

Conditional operator:-

The Conditional Operator in C, also called a Ternary operator, is one of the Operators, which used in the decision-making process. The C Programming Conditional Operator returns the statement depends upon the given expression result.

Example:-

Test_expression ? statement1: statement2

Special operator:-

OperatorDescriptionExample
sizeofReturns the size of an variablesizeof(x) return size of the variable x
&Returns the address of an variable&x ; return address of the variable x
*Pointer to a variable*x ; will be pointer to a variable x
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Operators

 22 Aug Admin

C operators are symbols that are used to perform mathematical or logical manipulations. The C programming language is rich with built-in operators. Operators take part in a program for manipulating data and variables and form a part of the mathematical or logical expressions.

Types of operators:-

C programming language offers various types of operators having different functioning capabilities.

  1. Arithmetic Operators
  2. Relational Operators
  3. Logical Operators
  4. Assignment Operators
  5. Increment and Decrement Operators
  6. Conditional Operator
  7. Bitwise Operators
  8. Special Operators

Arithmetic Operators:-

C supports all the basic arithmetic operators. The following table shows all the basic arithmetic operators.

OperatorDescription
+adds two operands
subtract second operands from first
*multiply two operand
/divide numerator by denominator
%remainder of division
++Increment operator – increases integer value by one
Decrement operator – decreases integer value by one

Relational operators:-

The following table shows all relation operators supported by C.

OperatorDescription
==Check if two operand are equal
!=Check if two operand are not equal.
>Check if operand on the left is greater than operand on the right
<Check operand on the left is smaller than right operand
>=check left operand is greater than or equal to right operand
<=Check if operand on left is smaller than or equal to right operand

Logical operators:-

C language supports following 3 logical operators. Suppose a = 1 and b = 0,

OperatorDescriptionExample
&&Logical AND(a && b) is false
||Logical OR(a || b) is true
!Logical NOT(!a) is false

Bitwise operators:-

Bitwise operators perform manipulations of data at bit level. These operators also perform shifting of bits from right to left. Bitwise operators are not applied to float or double(These are datatypes, we will learn about them in the next tutorial).

OperatorDescription
&Bitwise AND
|Bitwise OR
^Bitwise exclusive OR
<<left shift
>>right shift

Assignment Operators:-

Assignment operators supported by C language are as follows.

OperatorDescriptionExample
=assigns values from right side operands to left side operanda=b
+=adds right operand to the left operand and assign the result to lefta+=b is same as a=a+b
-=subtracts right operand from the left operand and assign the result to left operanda-=b is same as a=a-b
*=mutiply left operand with the right operand and assign the result to left operanda*=b is same as a=a*b
/=divides left operand with the right operand and assign the result to left operanda/=b is same as a=a/b
%=calculate modulus using two operands and assign the result to left operanda%=b is same as a=a%b

Conditional operator:-

The Conditional Operator in C, also called a Ternary operator, is one of the Operators, which used in the decision-making process. The C Programming Conditional Operator returns the statement depends upon the given expression result.

Example:-

Test_expression ? statement1: statement2

Special operator:-

OperatorDescriptionExample
sizeofReturns the size of an variablesizeof(x) return size of the variable x
&Returns the address of an variable&x ; return address of the variable x
*Pointer to a variable*x ; will be pointer to a variable x
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Data Types

 22 Aug  Admin

Each variable in C has an associated data type. Each data type requires different amounts of memory and has some specific operations which can be performed over it.Each variable in C has an associated data type. Each data type requires different amounts of memory and has some specific operations which can be performed over it.

Every C compiler supports five primary data types:

voidAs the name suggests, it holds no value and is generally used for specifying the type of function or what it returns. If the function has a void type, it means that the function will not return any value.
intUsed to denote an integer type.
charUsed to denote a character type.
float, doubleUsed to denote a floating point type.
int *, float *, char *Used to denote a pointer type.

Derived Data Types

C supports three derived data types:

Data TypesDescription
ArraysArrays are sequences of data items having homogeneous values. They have adjacent memory locations to store values.
ReferencesFunction pointers allow referencing functions with a particular signature.
PointersThese are powerful C features which are used to access the memory and deal with their addresses.

User defined data type

C allows the feature called type definition which allows programmers to define their identifier that would represent an existing data type. There are three such types:

Data TypesDescription
StructureIt is a package of variables of different types under a single name. This is done to handle data efficiently. “struct” keyword is used to define a structure.
UnionThese allow storing various data types in the same memory location. Programmers can define a union with different members, but only a single member can contain a value at a given time. It is used for
EnumEnumeration is a special data type that consists of integral constants, and each of them is assigned with a specific name. “enum” keyword is used to define the enumerated data type.
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HTML images

 HTML Images
 

  HTML images are defined within the <img> tag.
 The source file (src), alternative text (alt), width and height are  provided as attributes
 
<img src=”image.jpg” alt=”LearnersTV.in” width=”104″ height=”142″>
 

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HTML Lists

HTML Lists
HTML lists are defined with the <ul> (unordered/bullet list) or the <ol> (ordered/numbered list) tag, followed by <li> tags (list items)


<ul>
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ul>

<ol>
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>

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