Introduction
JavaScript is a kind of scripting language.
Scripting Languages are used to put logic with HTML tags. They are small
languages, having no environment. It is executed in browser with HTML.
All the scripting languages are Interpreted languages. There are some script languages, which are as follows:
- java Script :- Netscape
- Jscript :- MS (C/c++/java/c#)
- Vbscript :- MS (vb)
Why we use JavaScript
It is mainly used for Client side validations.
Fundamentals Of JavaScript
- There are no any specific data type (e.g. :-var t) in JavaScript.
- There are if, for, switch, while, do while, break, continue same as java or
c# in JavaScript.
- document.write() is used for display output in JavaScript.
- There are some dialogues in JavaScript, which are as follows
Alert -- Ok
Confirm -- Ok/CANCEL
Prompt -- Input - Function :-There are 'function' keyword used for function in JavaScript.
Some Examples of JavaScript:
Simple program of JavaScript.
<html>
<head>
<title>MY
TITLE</title>
</head>
<body>
<script type="text/javascript">
document.write("Most Welcome in JavaScript")
</script>
</body>
</html>
Output
If-else
program in JavaScript.
<html>
<body>
<script type="text/javascript">
var d = new
Date()
var time = d.getHours()
if (time < 10) {
document.write("<b>Good morning</b>")
}
else {
document.write("<b>Good day</b>")
}
</script>
<p>
This example
demonstrates the If...Else statement.
</p>
<p>
If the time on
your browser is less than 10,
you will get a "Good morning" greeting.
Otherwise you will get a "Good day" greeting.
</p>
</html>
Output
Switch case
in JavaScript.
<html>
<body>
<script type="text/javascript">
var d = new
Date()
theDay = d.getDay()
switch (theDay) {
case 5:
document.write("<b>Finally Friday</b>")
break
case 6:
document.write("<b>Super Saturday</b>")
break
case 0:
document.write("<b>Sleepy Sunday</b>")
break
default:
document.write("<b>I'm really looking
forward to this weekend!</b>")
}
</script>
<p>This
JavaScript will generate a different greeting based on what day it is. Note that
Sunday=0, Monday=1, Tuesday=2, etc.</p>
</body>
</html>
Output
For loop in
JavaScript.
<html>
<body>
<script type="text/javascript">
for (i = 0; i <= 5; i++) {
document.write("The number is " + i)
document.write("<br />")
}
</script>
<p>Explanation:</p>
<p>This
for loop starts with i=0.</p>
<p>As
long as <b>i</b>
is less than, or equal to 5, the loop will continue to run.</p>
<p><b>i</b>
will increase by 1 each time the loop runs.</p>
</body>
</html>
Output
While loop
in JavaScript.
<html>
<body>
<script type="text/javascript">
var i = 0;
while(i <= 5){
document.write("The number is " + i)
document.write("<br />")
i++
}
</script>
<p>Explanation:</p>
<p>This
while loop starts with i=0.</p>
<p>As
long as <b>i</b>
is less than, or equal to 5, the loop will continue to run.</p>
<p><b>i</b>
will increase by 1 each time the loop runs.</p>
</body>
</html>
Output
Do-while loop in JavaScript.
<html>
<<body>
<script type="text/javascript">
var i = 0;
do {
i++;
document.write("The number is " + i)
document.write("<br />")
}while(i<=5)
</script>
<p>Explanation:</p>
<p>This
do-while loop starts with i=0.</p>
<p>As
long as <b>i</b>
is less than, or equal to 5, the loop will continue to run.</p>
<p><b>i</b>
will increase by 1 each time the loop runs.</p>
</body>
</html>
Output
Break
statement in JavaScript.
<html>
<body>
<script type="text/javascript">
var i = 0;
for (i = 0; i <= 10; i++) {
if (i == 3) {
break;
}
document.write("The number is " + i);
document.write("<br />");
}
</script>
</body>
</html>
Output
Continue
statement in JavaScript.
<html>
<body>
<script type="text/javascript">
var i = 0
for (i = 0; i <= 10; i++) {
if (i == 3) {
continue;
}
document.write("The number is " + i);
document.write("<br />");
}
</script>
</body>
</html>
Output
Function in JavaScript.
<html>
<head>
<script type="text/javascript">
function product(a, b) {
return a * b
}
</script>
</head>
<body>
<script type="text/javascript">
document.write(product(4, 3))
</script>
<p>The
script in the body section calls a function with two parameters (4 and 3).</p>
<p>The
function will return the product of these two parameters.</p>
</body>
</html>
Output
