Showing posts with label javascript. Show all posts
Showing posts with label javascript. Show all posts

Monday 6 July 2020

conditional statements in javascript - Online Help

Conditional Statements in javascript:

Conditional statements in javascript are the set of commands used to perform different action s based on different conditions.  the conditional construct will either return a True or false depending upon how the condition is evaluated. There are two conditional statements in JavaScript:
  • if-else statement
  • switch statement

if-else statement :

Use this statement if you want to execute s set of code when a condition is true. If the condition is true the true statement is executed, otherwise, the false statement is executed.

The general format of the if-else statement is 

if (condition)
{
statement 1;                         
}           
else             
{             
statement 2;
}

The else clause allows you to specify a statement or group of statements that will be executed if the expression does not evaluate to true. Only one else clause is allowed in any if statement. Again, the statement can be used with or without the curly brackets.


Example:

<html>
<head>
<title> java script </title>
</head>
<body>
<b>RESULT</b>
<p> OPEN SOURCE SOFTWARE:
<script type=”text/java script”>
var m= 70; 
if (m>=35 && m<=100)
{
document. write (“<span style=’ color: blue ‘> PASS</span>”);
}
else
{
document. write(“<span style=’color : red’>FAIL</span>”);
}
</script>
</body>
</html>


switch statement in javascript:

The switch statement evaluates an expression and compares the value to one or more case clauses. If you need to compare a variable against more than two or three values, the switch statement is the most efficient way.

The general format of the switch statement is

 switch (expression)
{
case labe11: block1
break;
case labe12: block2 
break;
 ……………
default:     def block;
}

Evaluate an expression and attempt to match the expression’s value to a case label. If a match is found, the program executes the associated statement.

 

Example:

<html>
<head>
<title>java script</title>
</head>
<body>
<h2><font Color=”red”>SUBJECT&CODE</h2></font>
<script type=”text/java script”>
var subject code=”UCA61”;
switch (subject code)
{
case”UCA61”: subject=”Open Source Software”;
break;
case”UCA62”: subject=”Multimedia”;
break;
case”UPCA66”: subject=Open Source Laboratory”;
break;
default: subject=” UNKNOWN SUBJECT”;
}
document. write(“<h2>code=& nbsp” +subject code+”
<br> subject =&nbsp” +</h2>”);tement
</script>
</body>
</htm1>

I hope you guys understand what is a conditional statement in javascript. If you find any mistake or having any queries then please comment down below.



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Saturday 4 July 2020

Variables in javascript | Declaring a variable - Online help

In this post, we are going to talk about what is variables in javascript? and how to declare the variables in javascript. So stay tuned till the end and let's get started.

Variable in Javascript:

A variable in javascript is a name assigned to the computer memory location to store data. As the name suggests, the value of the variable can vary, as the program runs. Before you use a variable in a JavaScript program, you must declare it.  Variables are declared with the var keyword.


Variables in javascript | Declaring a variable - Online help


Rules for variable names:

  • They must begin with a letter, digit, or underscore character.
  • We can’t use spaces in names.
  • Variable names are case sensitive.
  • We can’t use a reserved word as a variable name.


Declaring JavaScript variable:

To declare the variable using the var keyword. You can declare one variable at a time or more than one. You can also assign values to the variables at the time you declare them.


Different methods of declaring JavaScript variables:

//declaring one JavaScript variable

var firstname;


//declaring multiple JavaScript variables

var firstname, lastname;


//declaring and assigning one JavaScript variable

var firstname= ’homer’;


//declaring and assigning multiple JavaScript variable

var firstname= ’homer’, lastname= ’simpson’;


JavaScript variable scope:

The scope of a variable is the region of your program in which it is defined. JavaScript variable will have only two scopes.

  • Global variables:  A global variable has a global scope which means it is defined everywhere in the JavaScript code.
  • Local variables: A local variable will be visible only within a function where it is defined. Function parameters are always local to the function.

Within the body of a function, a local variable takes precedence over a global variable with the same name. if you declare a local variable or function parameter with the same name as a global variable, you effectively hide the global variable. The following example explains it:

<script type= “text/javascript”>
<!—
Var myvar=”global”; // declare a global variable
Function checkscope()
{
Var myvar=”local”; //declare a local variable 
Document.write(myvar);
}
//-->
</script>

This produces the following result:
local

I hope you guys understand what is variables in javascript. If you find any mistake or having any queries then please comment down below. Thank you for reading.


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Friday 3 July 2020

Javascript functions | how to call javascript function - Online Help

Hello reader, today from this post we are going to learn about what is JavaScript functions? and how to call a function in javascript so read the article till the end and yeah let's gets started.

Javascript functions | how to call javascript function - Online Help


JavaScript functions:

Functions are a block of code that gets executed when called. Every function has a name, this name is used to call the function, which in turn result in the execution of the associate block of code. It takes zero or more parameters.

Functions can be defined both in the <head> and in <body> section of a document. However, to assure that a function is read or loaded by the browser before it’s called, it could be wise to put a function in the <head> section.


Defining functions:

A JavaScript functions definition consists of a function keyword, followed by the name of the function. A list of arguments to the function is enclosed in parentheses and separated by a comma. The statement within the function is enclosed in curly brace {}. The general format to define a function is,

Function functionname (parameter1, parameter2, …………..)
{
Statements;
}

Whereas,
  • Functionname is the name of the function.
  • parameter1, parameter2, ………….. are arguments or parameters to the function.


How to call functions in javascript:

A function is not executed before it is called. You can call functions containing arguments. The general form is:

functionname (parameter1, parameter2, …………..)


Return statement:

The return statement can be used to return any valid expression that evaluates to a sign value. A function that will return a result must use the return statement. This statement specifies the value which will be returned to where the function was called from.
A javascript function can have an optional return statement. This is required if you want to return a value from a function. The general format is,

return(); 

return(parameter);


Example:

<html>
<body>
<script type=”text/JavaScript”>
function funexample(a, b)
{
return a+b;
}
document.write (funexample(10,20));
</script>
</body>
</html>


Explanation:

The function is being called from another javascript method document.write. funexample() is a function passing two arguments 10 and 20.

Where 10 is being passed into the function funexample() as ‘a ‘ and 20 is being passed into the function as ‘b’.  

Once they are both passed in it return the sum of the two-argument. “return” simply means that we will return something back to the method or function that called our function funexample(). 

As a result, you can return sent back 30. The final statement that executed was more like document.write(30).


Example 2:

<html>
<head>
<title>example2</title>
</head>
<body>
<h2>
<script type=”text/JavaScript”>
functionsum(a, b)
{
c= a+b;
return c;
}
d= sum(12,8);
document.write (“the returned value is :” + d);
</script>
</h2>
</body>
</html>

The output of the above program is:

the returned value is: 20


Recursive function:

Recursion refers to the situation, wherein function call themselves. In other words, there is a call to specific functions from within the same function. It is called a recursive function.

Example:

<html>
<head>
<title>recursive function</title>
</head>
<body>
<script type= “text/JavaScript”>
var num=5;
function fact(num)
{
if (num>1)
{
document.write(“fact=”+num*fact(num-1));
}
else
{
document.write(“fact=”+num);
}
}
</script>
</body>
</html>

The result of the above program is,

Fact=120

I hope you guys understand what is javascript functions and how to define and call javascript functions. If you have any queries or doubt or you know more information about this article then please comment down below. Thank you for reading and visiting my blog.
.



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Thursday 2 July 2020

JavaScript operators | Types of operator in javascript - Online Help

Hello, readers today we are going to see what is javascript operators and types of the operator in detail. So let's gets started.


JavaScript operators | Types of operator in javascript - Online Help

Operators in javascript:

An operator is a symbol that tells the computer to perform certain mathematical and logical operations. Operators are used in a program to manipulate data and variables. 


Types of the operator in JavaScript:

The JavaScript language following type of operators:
  • Arithmetic operator
  • Comparison operator
  • Logical or relational operator
  • Assignment operator
  • Conditional or ternary operator
  • Bitwise operator

Let’s have a look on all operators one by one.


Arithmetical operator:

There are following arithmetical operator supported by JavaScript language:

Assume variable A holds 10 and variable B holds 20 then:

 Operator Description Example
 +  Adds two operands A+B will give 30
 - Subtract the second operand from the first  A-B will give -10
 * Multiply both operands A*B will give 200
 / Divide numerator by denominator  B/A will give 2
 %  Modulus operator and a reminder of after an integer division B%A will give 0
 ++  Increment operator, increases integer value by one.  A++ will give 11
 --  The decrement operator, decreases the integer value by one. A—will give 9

Example:

<html>
<head>
<title> Javascript</title>
</head>
<body>
<H2>
<script type=”text/javascript”>
var a=8;
var b=1;
document.write(“<h2>”+a+”+“+b+”=”+(a+b)+”<br></h2>”);
document.write(“<h2>”+a+”-“+b+”=”+(a-b)+”<br></h2>”);
document.write(“<h2>”+a+”*“+b+”=”+(a*b)+”<br></h2>”);
document.write(“<h2>”+a+”/“+b+”=”+(a/b)+”<br></h2>”);
</script>
</h2>
</body>
</html>

The output of the above program:
8+1=9
8-1=7
8*1=8
8/1=8


Javascript comparison operator:

There are following comparison operator supported by JavaScript language:

Assume variable A hold 10 and variable B holds 20 then:

 Operator Description Example
 == Checks if the value of two operands are equal or not, if yes then condition becomes true. (A==B) is not true
 != Checks if the value of two operands are equal or not, if the value is not equal then the condition becomes true.(A!=B) is true
 > Checks if the value of the left operands is greater than the value of right operand, if yes then condition becomes true.  (A>B) is not true
 < Checks if the value of the left operand is less than the value of right operand, if yes then the condition becomes true. (A<B) is true
 >= Checks if the value of the left operand is greater than or equal to the left operand, if yes then the condition is true. (A>=B) is not true
 <= Checks if the value of the right operand is less than or equal to the value of right operand, if yes then the condition is true.  (A<=B) is true

Example:

<html>
<head><title>Comparison operator</title></head>
<body>
<h2>
<script type=”text/javascript”>
var a=200;
var b=300;
if(a>b)
document.write(“A is greater than B”);
else
document.write(“B is greater than A”);
</script>
</h2>
</body>
</html>


Logical operator:

These are the following logical operators supported by javascript.

Assume that variable  A holds 10 and variable  B holds 20 then:

 Operators Description Example
 && && is called a logical AND operator. If both the operands are non-zero then the condition becomes true.  (A&&B) is true
 || || is called a logical OR operator. If any of the two operands are non zero then the condition becomes true (A||B) is true
 ! ! is called logical NOT. Use to reverse the logical state of its operands. If a condition is true then the logical NOT operator will make false. !(A&&B) is false

Example:

<html>
<head><title>Logical operator</title></head>
<body>
<h2>
<script type=”text/javascript”>
var marks1=24;
var marks2=35;
if(mark1>40 && marks2=>40)
document.write(“ pass”);
else
document.write(“fail”);
</script>
</h2>
</body>
</html>
The output is:
fail


Bitwise operator:

These are the following bitwise operator supported by the javascript language.

Assume that the variable A holds 2 and variable B holds 3 then:

 Operator Description Example
 & Called bitwise AND operator. It performs Boolean AND operation on each bit of its integer argument.

 (A&B) is 2
 |  Called bitwise OR operator. It performs Boolean OR operation on each bit of its argument. (A|B) is 3
 ^ Called bitwise XOR operator. It performs a Boolean exclusive OR operation on each biut of its integer arguments. Exclusive OR means that either operand one is true or operand two is true, but not both. (A^B) is 1
 ~ Called bitwise NOT operator. It is a unary operator and operates by reversing all bits in the operands (~B) is -4
 << Called bitwise shift left operator.it moves all bits in its first operand to the left by the number of places specified in the second operand.

New bits are filled with zero. shifting a value left by one position is equivalently multiplying by 2, shifting 2 positions is equivalent to multiplying by 4, etc.,		 (A<<1) is 4
 >> Called bitwise shift right with sign operator.it moves all the operands to the right by the number of places specified in the second operand.

The bits filled in on the left depends on the sign bit of the original operand, in order to preserve the sign of the result.

If the first operand is positive, the result has zeroes placed in the high bits; if the first operands are negative, the result has ones placed in the high bit.

 Shifting a value right one place is equivalent to dividing by 2(discarding the reminder), shift right two places is equivalent to integer division by 4, and so on
 (A>>1) is 1
 >>>  This operator is called a bitwise shift right with zero operators. This operator is just like the >> operator, except that the bits shifted in on the left are always zero,  (A>>>1) is 1


Assignment operator:

These are the following assignment operators supported by the javascript language:

 Operator  Description Example
 =  A simple assignment operator assigns a value from right side operands to left side operand
C=A+B will assign the value of A+B into C
 +=  Add AND assignment operator, it adds right operands to left operands and assigns the result to the left operand. C+=A is equivalent to C=C+A
 -= Subtract AND assignment operator, it subtracts right operands to left operands and assigns the result to the left operand.C-=A is equivalent to C=C-A
 *= Multiply AND assignment operator, it multiplies right operands to left operands and assigns the result to the left operand.C*=A is equivalent to C=C*A
 /= Divide AND assignment operator, it divides right operands to left operands and assigns the result to the left operand.C/=A is equivalent to C=C/A
 %= Modulus AND assignment operator takes modulus using two operands and assigns the result to the left operand.C%=A is equivalent to C=C%A

Example:

<html>
<head><title>Assignment operator</title></head>
<body>
<script type=”text/javascript”>
var a=1980;
var b=1985;
document.write(a+”++”+b+”=”+(a==b)+”<br>”);
document.write(a+”>=”+b+”=”+(a>=b)+”<br>”);
document.write(a+”<=”+b+”=”+(a<=b)+”<br>”);
</script>
</body>
</html>

The output is:
1980==1985=false
1980>=1985=false
1980<=1985=true


Ternary operator javascript/conditional operator:

There is an operator called a conditional operator. It is also called a ternary operator. this operator first evaluates an expression for a true or false value and then execute one of the two given statement depending upon the result of the evaluation. The conditional operator has this syntax:

 Operator description Example
 ?:Conditional expression  
If the condition is true? Then value X: Otherwise value Y


Example:

<html>
<head><title>Logical operator</title></head>
<body>
<h2>
<script type=”text/javascript”>
var a=24;
var b=20;
document.write(a>b ? ”true”: “false”);
</script>
</h2>
</body>
</html>

The output is:
true

I hope you guyz understand what is javascript operators and types of operators in detail. If you have any queries or you guys find any mistake then please comment down below. Thank you for reading.


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Thursday 25 June 2020

Advantages of Javascript - Online Help

Advantages of JavaScript:

 The following are the advantages of JavaScript:

  • JavaScript is relatively secure
  •  It is widely supported in browsers
  •  It gives easy access to document object and can manipulate most of them
  •  JavaScript can give interesting animations with many multimedia data types
  •  The special plugin is not required to use JavaScript
  •  JavaScript is a secure language
  •  JavaScript code resembles the code of C language the syntax of both the language is very close to each other. The set of tokens and constructs are the same in both the language
  •  Less server interaction
  •  Immediate feedback to the visitors
  •  Increased interactivity
  •  Richer interfaces
  •  The web server doesn't need a special plugin to use your scripts

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Thursday 11 June 2020

Uses of javascript | What is javascript used for - Online help

hello readers, in the last post we have discussed the javascript introduction briefly so now in this post, we'll see the uses of javascript?

Uses of javascript | What is javascript used for - Online help

Uses of JavaScript:

The JavaScript was initially introduced to provide programming capability at both the server and client ends of web connection.

JavaScript, therefore, is implemented at two ends:
  •  client end
  •  back end
The client-side JavaScript is embedded in XHTML documents and is interpreted by the web browser.

It also provides some means of computation, which serves as an alternative for some tasks done at the server-side.

Interaction with users through form elements, such as button and menus, can be conveniently described in JavaScript. Because button clicks and mouse movements are easily detected with JavaScript, they can be used to trigger computations and provide feedback to the user.

For example, when a user Moves the mouse cursor from the textbox, JavaScript can detect that moment and check the appropriateness of the textbox’s value(which presumably was just filled by the user).

Even without forms, user interaction is both possible and simple to the program in JavaScript. These interactions, which take place in the dialogue Windows, includes getting input from the user and allowing the user to make choices through the buttons. It is also easy to generate new content in the browser displays dynamically.

This transfer of tasks ensures that the server is not overloaded and performs only the required task.

But client-side JavaScript cannot replace servers side JavaScript; because server-side software supports file operation, database access, security, and networking, etc.

JavaScript is also used as an alternative to Java applets.

Programming in JavaScript is must simpler than compared to Java

JavaScript support DOM (document object model) which enables JavaScript to access and modify CSS properties and content of any element of a displayed XHTML document.

I hope you guys understand the uses of the javascript. If you have any queries or you find any mistake please comment down below. 
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Wednesday 10 June 2020

What is JavaScript used for in web design - Online Help

What is JavaScript used for in web design:

Hello, readers in this post we will gonna see what is JavaScript used for in web design. let's get started.

What is JavaScript used for in web design - Online Help

The primary use of JavaScript is to write functions that are embedded in or included from HTML pages and interact with the document object model(DOM)of the page. Some simple examples of  this usage are:
  • Opening or popping up a new window with programmatic control over the size, position, and attributes of the new window(i.e. whether the menus, toolbar, etc are visible). 
  • Validation of web form input value to make sure that they will be accepted before they are submitted to the server.
  • Changing images as the mouse cursor moves over them: This effect is often used to draw the user's attention to important links displayed as graphical elements.
Because JavaScript code can run locally in the user's browser(rather than on the remote server) it can respond to user action quickly, making an application feel more responsive.

Furthermore, JavaScript code can detect user actions with HTML alone cannot, such as individual keystrokes.

An application such as Gmail takes advantage of this: much of the user interface logic is written in JavaScript, and Javascript dispatches requests for the information(such as the content of an email message) to the server.

So guys let's see what can a Javascript do.

Also read:  Multithreading in java

what can a JavaScript do:

JavaScript gives web developers a programming language for the use in the web pages and allows them to do the following:

JavaScript gives HTML designer a programming tool: 

HTML authors are normally not programmers, but JavaScript is a scripting language with a very simple Syntax! almost anyone can put simple "snippets" of code into their HTML pages.


JavaScript can put dynamic text into HTML pages:   

A JavaScript statement like this: document.write("<h3>"+name+"</h3>") can write a variable text into HTML page.


JavaScript can react to events:

A JavaScript can be set to execute when something happens like when a page has finished loading or when a user clicks on the HTML element.


JavaScript can read and write HTML elements:

A JavaScript can read and change the content of the HTML element.

Also Read: Thread in java

JavaScript can be used to validate data:

A JavaScript can be used to validate form data before it is submitted to the server. This saves the server from extra processing.


JavaScript can be used to detect the visitor's Browser:

A JavaScript can be used to detect the visitor's browser and depending on the Browser-load another page specifically designed for that browser.


JavaScript can be used to create cookies:

A JavaScript can be used to store and retrieve information on the visitor's computer.

Also read: Exception handling in java

So guys here I had briefly explained what is JavaScript used for in web design. I hope you guys understand the uses of JavaScript in web design if you have any doubts please comment in the comment section below. Thank you for visiting and reading my site.

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Tuesday 9 June 2020

Javascript introduction| what is Javascript| History of javascript -Online Help

Javascript Introduction:

The important topic of web technology is JavaScript. Now, what is JavaScript let's see the JavaScript introduction?
Javascript introduction| what is Javascript| History of javascript -Online Help
JavaScript is a client-side scripting language and connected to the server.

It is widely used in tasks ranging from validation of form data to the creation of complex user interfaces.

Javascript is a dynamic computer programming language and powerful client-side scripting language. It is mainly designed for enhancing the interaction of the user with the web pages.

JavaScript not only used in web pages but also used in many desktop and server programs as well as in-game development and mobile application development.

Dynamic HTML is a combination of the content formatted using HTML, CSS, scripting language, and DOM by combining all of these technologies we can create an interesting and interactive website.

History of JS:

Netscape initially introduced the language under the name LiveScript in an early beta release of navigator 2.0 in 1995, and the focus was on form validation. After that, the language was renamed JavaScript.

After Netscape introduced JavaScript in version 2.0 of their browser, Microsoft introduced a clone of JavaScript call JS script in internet explorer 3.0.

Also read: Java string | string classes in java

What is JavaScript?

  • JavaScript was designed to add interactivity to the HTML pages.
  • JavaScript is a scripting language.
  • It is the lightweight programming language.
  • JavaScript is usually embedded directly into HTML pages.
  • JavaScript is an interpreted language that means which executes without preliminary completion.
  • Everyone can use JavaScript without purchasing a license.

Are Java and JavaScript the same?

No, Java and JavaScript are not the same. In fact, they are completely different languages in both concepts and designs.

Java {developed by Sun Microsystem} is a powerful and much more Complex program - in the same category as C and C++.

Let's see the comparison between Java and Javascript:

Java

JavaScript

  • Java is a programming language
  • JavaScript is a scripting language
  • It is strongly typed language
  • It is dynamically typed language
  • Types on own at the compile time
  • Compile-time type checking is impossible
  • The objects in Java is static
  • Javascript Object are dynamic
  • Collection of data member and the method is fixed at the compilation time
  • The number of data member and methods of an object can change during execution
  • Object-oriented programming language
  • Object-based language

I hope you guys understand what is JavaScript and the introduction briefly. Let's see the uses and advantages of it in the next post if you have any queries please comment down below. Thank you for visiting my site.
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