JavaScript(JS)
JavaScript scripting language , which is used to enhance the functionality and appearance of web pages.
All web browser have JavaScript interpreters.
JavaScript is a browser-based Scripting language developed by Netscape and implemented in all major browsers.
Scripts can be Static or Dynamic.
JavaScript is Case Sensitive.
JS Memory Concepts - similar to Java/C.
Sample Program
You want to open Notepad , it is a default software in your system. After typing the code , you want to save the file as ".html" (eg: 1.html like this you want to save your file).
<!DOCTYPE html>
<html>
<head>
<meta charset =''utf-8">
<title>A first program in JavaScript</title>
<script type="text/javascript">
document.writeln("<h1> Welcome to JavaScript Programming!</h1>");
</script>
</head>
<body></body>
</html>
Result
You can view your result in the web browser like Internet explorer , Chrome , Firefox etc.,.
To implement the Function , Arrays and Objects using JavaScript
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| JavaScript Program |
Escape Sequences in JavaScript
- \n - New Line - Position the screen cursor at the beginning of the next line.
- \t - Horizontal Tab - Move the screen cursor to the next line.
- \\ - Backslash - Used to represent a backslash character in a string.
- \" - Double quote - Used to represent a double-quote character in a string contained in double quotes. For Example : window.alert("\" in double quotes\""); Displays "in double quotes" in an alert dialog.
- \' - Single quote - Used to represent a Single-quote character in a string. For Example : window.alert("\" in single quotes\""); Displays "in Single quotes" in an alert dialog.
- // - Forward slash - Single line Comment that begins with the character // states the purpose of the variable in the script. For Example : // read the name from the prompt box as a string name= window.prompt("Please enter your name"); // covert numbers from strings to integers number1= parseInt(firstnumber);
- /*....*/ - Backslash and star - Multiline Comment - It can be split over many lines. For Example : /* It can be split over many lines. */
Data Types of JavaScript
Loosely Defined Data types- Can hold any type of data.
- Arithmetic - Addition(+) , Subtraction(-) ,Multiplication(*) ,Division( /) ,Remainder (%).
- Decision making (if statement) : Equality operators - Equal(==) , Not Equal(!=). Relational Operator - Greater than(>) , Lesser than(<) , Greater than or equal to (>=) , Lesser than or equal to(<=).
- Strict Equals(===) and Strict Does Not Equals(!==) Operators. For Example : comparison "95" === 95 yields the value false because one is string and the other one is number. Similarly 95" !== 95 yields true because the operand 's type are not equal ,therefore the values are not equal.
Format/Syntax:
Function Call:
function functionname(parameter-list)
{
declarations and statements
}
return statement;
return expression; (or) return;
What is Array in javascript?
In JavaScript Array is a single variable that is used to store different elements. There are basically two ways to declare an array.
Array is a Dynamic . Size of the array in JavaScript can be changed.
Arrays knows their length(length property).
Arrays in Memory : Objects and Operator or new(Allocates memory for objects and Dynamic memory allocation operator). Eg: var c;
c= new Array(12)
Program
- Open the Notepad(HTML editor)
- Script must contain in head section
- Code for Array must be written inside the script.
- Use the Syntax build the codes for the respective functions.
- Save the html program using .html extension.
Reversing the Array
<html>
<head>
<meta charset ="utf-8">
<title>Sample Array</title>
<script type="text/javascript">
function start()
{
var a =[10,20,30,40,50,60,70,80,90,100];
document.writeln("<h1>Reversing the array</h1>");
outputArray("Data items in original order:",a);
a.reverse(swap);
outputArray("Data items in reverse order:",a);
}
function outputArray(header, theArray)
{
document.writeln("<p>"+header+theArray.join(" ")+"<p>");
}
function swap()
{
for(a=0;a>=0;a--)
{
return a;
}
}
</script>
</head>
<body onload="start()"></body>
</html>
Result
You can view your result in the web browser like Internet explorer , Chrome , Firefox etc.,.
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| Array JavaScript |
What is Object in javascript?
Objects in javascript may be defined as an unordered collection of related data of primitive or reference types in the form of "Key: value" pair.
Program
- Open the Notepad(HTML editor)
- Script must contain in head section
- Code for Object must be written inside the script.
- Use the Syntax build the codes for the respective functions.
- Save the html program using .html extension.
Object(Click button to view Math.Round function answer)
<html>
<head>
<title>Object</title>
<script type="text/javascript">
function md()
{
document.getElementById("demo").innerHTML=Math.Round(2.5);
}
</script>
</head>
<body>
<p id="demo"> Click the button</p>
<button onclick="md()">Click</button>
</body>
</html>
Result
You can view your result in the web browser like Internet explorer , Chrome , Firefox etc.,.
 |
| Object JavaScript 1.1 |
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| Object JavaScript 1. 2 |
What is Function in javascript?
JavaScript functions are defined with the function keyword. We can use a function declaration or a function expression. In javascript functions are objects and they have both properties and methods.
Program
- Open the Notepad(HTML editor)
- Script must contain in head section
- Code for Function must be written inside the script.
- Use the Syntax build the codes for the respective functions.
- Save the html program using .html extension.
Recursion of Fibonacci Function
<html>
<head>
<title>Recursion of Fibonacci Function</title>
<h1>Recursion of Fibonacci Function for 0 to 10</h1>
<script type="text/javascript">
for(var i=0;i<=10;i++)
{document.write("<br> Fibonacci of " + i +" is "+fibonacci(i)); }
function fibonacci(num)
{
if(num==0)
return 0;
if (num == 1)
return 1;
else
return fibonacci(num - 1) + fibonacci(num - 2);
}
</script>
</head>
</html>
Result
You can view your result in the web browser like Internet explorer , Chrome , Firefox etc.,.
"JavaScript(JS)" easy for beginners to learn and Understand .
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