computer tips

A MAN ( Metropolitan Area Network) is used to connect computers to cover the city or town. The range may be approximately 50 Kilometers. Normally  cables and fiber optic cables are used to connect computers. The routing of the messages are fast.  Normally central library in a city may be connected by a MAN, so users can access the information. Figure 5.2 shows a typical view of Metropolitan Area Network.

Figure 5.2 Metropolitan Area Network

Wide Area Network (WAN)earn money online

            A WAN (Wide Area Network) covers large distance like state, country or continents. The WAN uses the fiber optics, cables and even satellites also. Here communication circuits are connected with the help of hardware device called routers. Routers forward small pieces of information called packets from one to another.  Internet is the popular one comes under WAN.  Some of the examples makes use of internet are reservation of airplane tickets, railway tickets and even cinema tickets. Another facility called  e-commerce, where business is carried out through internet. Here people can buy books, articles and so on through registering their wants through the internet. Figure 5.3 shows a typical view of Wide Area Network.

Fig 5.3 Wide Area Network

5.3 Internet

            The internet is a massive wide area network  ,connecting thousands of computer networks around the world. The internet is a world wide “network of networks”. It is a collection of thousands of smaller networks in different countries around the world. It links thousands of academic government, military and public computers, enabling millions of people to share information and other resources.

            Internet pathways are used to exchange digitized computer data. The basic services that form the foundation of the internet are e-mail , telnet and FTP. With internet we can easily exchange electronic mail with friends and family anywhere in the world.

            Telnet allows you to connect to a remote computer. We can access any of the public services or tools and library databases at the remote site. FTP(File Transfer Protocol) provides for transferring files from one computer to another across the internet.

            Internet has many uses. For individuals, the most important uses of internet are e-mail and surfing the Web. One can read the topics of interest like sports, a hobby, a country or any place of interest.

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The e-mail stands for electronic mail. One of the major features of computer networking is that messages can be sent electronically to various terminals on the network. The messages are sent very quickly and accurately. E-mail uses the concept of Storing and forwarding messages. It saves a lot of money for the users. Here user registers his/her account with one of the providers. The e-mail account normally contains username and the provider name. For example abc @ yahoo.com , represents abc is the name of the user , who is registered in yahoo provider. 

1.4  Summary:

• Computer network is defined as a interconnection of autonomous  computers.

• Computer networking  enables us to connect computers to share data, application software and hardware devices.
• Networks allow sharing of information among various computers and permit users to share files.
• A LAN or local area network connects computers and peripherals in a limited area.
• A MAN covers the city or town.
• A Wide Area Network covers  a large area.
• The internet is a massive wide area network, connecting thousands of computer networks around the world.
• E-mail is  a cost effective communication

5.5 Quiz questions

1. Computer network defined as a interconnection of  ----------  computers

       2. Computer network allows user to  ----- the resources

       3. -------- network confined to hall or building.

       4. ------- is one example of WAN.

       5. ------ business is carried our through internet.

        6. Small piece of information called ---- are forwarded by router  in Internet.

JavaScript IndexOf

JavaScript IndexOf() method Performs a case-sensitive search and returns the indexof the first occurrence of the specified substring in the calling String object argument, starting the search at the beginning of the string.

 

JavaScript Prototype

Category: Javascript String

A JavaScript Prototype is an object from which other objects inherit properties. Every object has a prototype by default. An object in JavaScript is any unordered collection of key-value pairs. If it’s not a primitive (undefined, null, Boolean, number or string) its an object.

 

JavaScript Match() Method

Category: Javascript String

JavaScript Match() Method compares a regular expression and a string to see whether they match. It returns an array containing one or more matches, depending on how it is used. If no match is found, it returns –1.

 

JavaScript search() Method

Category: Javascript String

JavaScript search() Method: Whenever working with a strings, sometimes we need to determine if a string contains some specific substring, and if it does, you need to determine where in the string that substring occurs.

 

JavaScript SubString

Category: Javascript String

JavaScript SubString Strings are constructed of characters. The JavaScript SubString method returns a set of characters within its calling String object. Its general syntax of JavaScript SubString method:

var NewSubstring = NewSubstring.substring (StartingPosition, EndPosition)

 

JavaScript Split Method

Category: Javascript String

JavaScript Split Method: A delimiter is a sequence of one or more characters used to specify the boundary between separate, independent regions in plain text or other data streams. An example of a delimiter is the comma character, which acts as a field delimiter in a sequence of comma-separated values; each of the substrings is an element in the list.

 

JavaScript Length

Category: Javascript String

JavaScript Length; You will often find it necessary to count characters and words in strings, particularly with strings from form submissions. For example, you might need to count the number of characters in a password to ensure that a user selects a password with a minimum number of characters.

 

JavaScript String Format

Category: Javascript String

JavaScript String Format:  When you create a text string in JavaScript, a string object is associated with that string. The string object provides a series of methods you can use to adjust the format of the string. JavaScript String Format can be useful when you want to display a string and quickly apply some formatting to it. The JavaScript String Format are as follows:

 

JavaScript replace() Method

Category: Javascript String

JavaScript replace() Method: To replace information in a string, you can use regular expressions and the JavaScript replace() Method of the String object. The syntax for using the JavaScript replace() Method is as follows:

 

JavaScript Blink Method

Category: Javascript String

JavaScript Blink Method: JavaScript Blink Method is used to display a specified string in blink tags. JavaScript Blink Method returns the string with the tag <BLINK> surrounding it, like this: <blink>string</blink>

 

JavaScript Substr Method

Category: Javascript String

JavaScript Substr Method: If you wanted to pulls out a portion of a string and assign that cut-out part to another variable or use it in an expression, you would use the JavaScript Substr Method.

 

JavaScript Anchor

Category: Javascript String

The JavaScript Anchor is a string function that can be accessed using dot operator with string variable. It transforms the specified text into hypertext.

 

Difference Between Slice Substr and Substring

Category: Javascript String

That’s right; there are three methods for getting part of a string out of a larger string. First, you can use slice. It takes two parameters: the first parameter is the starting index, and the second one is the ending index, meaning the index of the character after the last character in the desired substring. If you leave the second one off, it will slice until the end of the string.

 

JavaScript String Object

Category: Javascript String

JavaScript String Object: Strings are an important part of any programming language. Whether you are storing a person’s last name or the name of a product in inventory, a string is often the best way to store that value. A string is any text inside a quote pair. A quote pair consists of either double quotes or single quotes.

 

JavaScript Constructor

Category: Javascript String

This JavaScript Constructor property performs the same task as it does in the other objects that have it (like the Date and Array objects). . It sends back the value of the JavaScript Constructor function that created the String object's prototype. To use the JavaScript Constructor property, you have to use a String object rather than a literal

 

JavaScript Big Method

Category: Javascript String

JavaScript Big Method: JavaScript Big Method is used to display a specified string in a big size font. JavaScript Big Method returns the string with the tag <BIG> surrounding it, like this: <big>string</big>

What is HTML?

What is HTML?At its most fundamental, Hypertext Markup Language (HTML) is a set of special codes that you embed in text to add formatting and linking information. HTML is based on Standard Generalized Markup Language (SGML). By convention, all HTML information begins with an open angle bracket (<) and ends with a closing angle bracket (>), for example, <html>.

 

HTML TABINDEX

Category: HTML

Now we will be discussing how to navigate through a particular form. By default, you navigate through the form in the order in which elements appear in the form, using tab index attribute you can change this default order. Just place the tabindex attribute in the input field. Our sample form shows the following fields and they will be accessed in the order they are listed. Using the tabindex attribute the order will change. The following code shows the new order as below:

 

HTML INPUT TYPE FILE

Category: HTML

HTML also supports a special input field, a file field, to allow visitors to upload files. If you want visitors to submit information - say a picture, a spreadsheet, a word-processed document or a scanned document, they can use this field to simply upload the file with the hassle of using FTP or e-mail the file.

 

HTML TABLE

Category: HTML

A table is an orderly arrangement of data distributed across a grid of rows and columns similar to a spreadsheet. In printed documents, tables commonly serve a subordinate function, illustrating some point described by accompanying text. Tables still perform this illustrative function in HTML documents.

 

HTML TABLE BACKGROUND IMAGE

Category: HTML

An image can either be included in a table cell or can act as a background in a table:

1. To add a background image: Use "background" attribute in the opening <TABLE>tag. It will take the URL of the image as its value and the background images are titled throughout the available table space.

 

HTML UL - Unordered lists - Bulleted lists

Category: HTML

Unordered lists are used to represent a set of items that have a relation among themselves but do not follow a specific order. The syntax is same as that of ordered list, only <OL> and </OL> tags are replaced by <UL> and </UL>.

 

HTML FORM

Category: HTML

An HTML form is a section of a web document into which the user can enter information. This information is passed back to a web server where it might be recorded in a database for future use or perhaps used to control what information is returned to the user.

 

HTML HR

Category: HTML

If what is needed is to separate two different sections of a page, whether text or not, may be employed new label: <hr>. Its name comes from English Horizontal Rule (horizontal line). This label is formed by a single instruction and causes the browser to insert a horizontal line it separating the two paragraphs that were being compared. There are four attributes that allow change its appearance. These are:

 

HTML MARQUEE

Category: HTML

This tag is used to scroll text horizontally across the screen. It is mainly used to deliver a specific message to the visitor or to scroll Ads on a page. It is not a standard HTML tag and so the browser support for it is typically limited to Internet explorer.

 

COMMON GATEWAY INTERFACE

Category: HTML

The Common Gateway Interface (CGI) is a specification defined by the World Wide Web Consortium (W3C), defining how a program interacts with a Hyper Text Transfer Protocol (HTTP) server. The Common Gateway Interface (CGI) provides the middleware between WWW servers and external databases and information sources. CGI applications perform specific information processing, retrieval, and formatting tasks on behalf of WWW servers.