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B Y G O U R I S H A N K A R R P U J A R
JavaScript
Introduction
1. HTML to define the content of web pages
2. CSS to specify the layout of web pages
3. JavaScript to program the behaviour of web pages
 JavaScript Can Change HTML Content
 document.getElementById("demo").innerHTML = "Hello
JavaScript";
 JavaScript Can Change HTML Styles (CSS)
 document.getElementById("demo").style.fontSize = "35px";
 JavaScript Can Hide HTML Elements
 document.getElementById("demo").style.display = "none";
 JavaScript Can Show HTML Elements
 document.getElementById("demo").style.display = "block";
 JavaScript Where To ?
<script>
document.getElementById("demo").innerHTML = "My First
JavaScript";
</script>
<p id="demo"></p>
Functions
<script>
function myFunction() {
document.getElementById("demo").innerHTML = "Paragraph
changed.";
}
</script>
<h1>A Web Page</h1>
<p id="demo">A Paragraph</p>
<button type="button" onclick="myFunction()">Try it</button>
Tips
 You can Place JavaScript tag inside HTML in any Part like
<head>
<script> Test Function </script>
</head>
<body>
You can write all your mark-up Here.
<script> Test Function </script>
</body>
Tips
 You can Include all functions in External sheet & call
them in respective page.
 As like We have did in CSS – External Stylesheet
 Like that we can also have External Script.
 <script src=“script.js”></script>
JavaScript Output
 JavaScript can "display" data in different ways:
 Writing into an HTML element, using innerHTML.
 Writing into the HTML output
using document.write().
 Writing into an alert box, using window.alert().
 Writing into the browser console,
using console.log().
 document.getElementById("demo").innerHTML = 5 + 6;
 document.write(5 + 6);
 <button type="button" onclick="document.write(5 + 6)">Try
it</button>
 window.alert(5 + 6);
 console.log(5 + 6);
JavaScript Statements
 var x, y, z; // Statement 1
x = 5; // Statement 2
y = 6; // Statement 3
z = x + y; // Statement 4
 var a, b, c; // Declare 3 variables
a = 5; // Assign the value 5 to a
b = 6; // Assign the value 6 to b
c = a + b; // Assign the sum of a and b
to c
 var x, y; // How to declare
variables
x = 5; y = 6; // How to assign values
z = x + y; // How to compute
values
 Fixed values are called literals. Variable values are
called variables.
 Strings are text, written within double or single quotes:
JavaScript Variables
 In a programming language, variables are used to store data
values.
 JavaScript uses the var keyword to declare variables.
 An equal sign is used to assign values to variables.
var x;
x = 6;
Operations
 document.getElementById("demo").innerHTML = "John" + " "
+ "Doe";
 var x, y;
x = 5 + 6;
y = x * 10;
 Numbers are not allowed as the first character.
This way JavaScript can easily distinguish identifiers from
numbers.
Comments
 Code after double slashes // or between /* and */ is treated as
a comment.
 var x = 5; // I will be executed
// var x = 6; I will NOT be executed
Tips
 All JavaScript identifiers are case sensitive.
 The variables lastName and lastname, are two different
variables.
 JavaScript does not interpret VAR or Var as the keyword var.
 In JavaScript, the first character must be a letter, or an underscore
(_), or a dollar sign ($).
 Hyphens are not allowed in JavaScript. They are reserved
for subtractions.
Variables
var price1 = 5;
var price2 = 6;
var total = price1 + price2;
<p id="demo"></p>
<script>
var carName = "Volvo";
document.getElementById("demo").innerHTML = carName;
</script>
 var person = "John Doe", carName = "Volvo", price = 200;
 If you put a number in quotes, the rest of the numbers will be
treated as strings, and concatenated.

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Java script

  • 1. B Y G O U R I S H A N K A R R P U J A R JavaScript
  • 2. Introduction 1. HTML to define the content of web pages 2. CSS to specify the layout of web pages 3. JavaScript to program the behaviour of web pages
  • 3.  JavaScript Can Change HTML Content  document.getElementById("demo").innerHTML = "Hello JavaScript";  JavaScript Can Change HTML Styles (CSS)  document.getElementById("demo").style.fontSize = "35px";
  • 4.  JavaScript Can Hide HTML Elements  document.getElementById("demo").style.display = "none";  JavaScript Can Show HTML Elements  document.getElementById("demo").style.display = "block";
  • 5.  JavaScript Where To ? <script> document.getElementById("demo").innerHTML = "My First JavaScript"; </script> <p id="demo"></p>
  • 6. Functions <script> function myFunction() { document.getElementById("demo").innerHTML = "Paragraph changed."; } </script> <h1>A Web Page</h1> <p id="demo">A Paragraph</p> <button type="button" onclick="myFunction()">Try it</button>
  • 7. Tips  You can Place JavaScript tag inside HTML in any Part like <head> <script> Test Function </script> </head> <body> You can write all your mark-up Here. <script> Test Function </script> </body>
  • 8. Tips  You can Include all functions in External sheet & call them in respective page.  As like We have did in CSS – External Stylesheet  Like that we can also have External Script.  <script src=“script.js”></script>
  • 9. JavaScript Output  JavaScript can "display" data in different ways:  Writing into an HTML element, using innerHTML.  Writing into the HTML output using document.write().  Writing into an alert box, using window.alert().  Writing into the browser console, using console.log().
  • 10.  document.getElementById("demo").innerHTML = 5 + 6;  document.write(5 + 6);  <button type="button" onclick="document.write(5 + 6)">Try it</button>  window.alert(5 + 6);  console.log(5 + 6);
  • 11. JavaScript Statements  var x, y, z; // Statement 1 x = 5; // Statement 2 y = 6; // Statement 3 z = x + y; // Statement 4  var a, b, c; // Declare 3 variables a = 5; // Assign the value 5 to a b = 6; // Assign the value 6 to b c = a + b; // Assign the sum of a and b to c
  • 12.  var x, y; // How to declare variables x = 5; y = 6; // How to assign values z = x + y; // How to compute values  Fixed values are called literals. Variable values are called variables.  Strings are text, written within double or single quotes:
  • 13. JavaScript Variables  In a programming language, variables are used to store data values.  JavaScript uses the var keyword to declare variables.  An equal sign is used to assign values to variables. var x; x = 6;
  • 14. Operations  document.getElementById("demo").innerHTML = "John" + " " + "Doe";  var x, y; x = 5 + 6; y = x * 10;  Numbers are not allowed as the first character. This way JavaScript can easily distinguish identifiers from numbers.
  • 15. Comments  Code after double slashes // or between /* and */ is treated as a comment.  var x = 5; // I will be executed // var x = 6; I will NOT be executed
  • 16. Tips  All JavaScript identifiers are case sensitive.  The variables lastName and lastname, are two different variables.  JavaScript does not interpret VAR or Var as the keyword var.  In JavaScript, the first character must be a letter, or an underscore (_), or a dollar sign ($).  Hyphens are not allowed in JavaScript. They are reserved for subtractions.
  • 17. Variables var price1 = 5; var price2 = 6; var total = price1 + price2; <p id="demo"></p> <script> var carName = "Volvo"; document.getElementById("demo").innerHTML = carName; </script>
  • 18.  var person = "John Doe", carName = "Volvo", price = 200;  If you put a number in quotes, the rest of the numbers will be treated as strings, and concatenated.