JavaScript - Part-1


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JavaScript Part-1

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JavaScript - Part-1

  1. 1. Java Script What is JavaScript? JavaScript was designed to add interactivity to HTML pages. JavaScript is a scripting language. A scripting language is a lightweight programming language. JavaScript is usually embedded directly into HTML pages. JavaScript is an interpreted language (means that scripts execute without preliminary compilation). Everyone can use JavaScript without purchasing a license.
  2. 2. Java Script What can a JavaScript do? JavaScript gives HTML designers a programming tool - HTML authors are normally not programmers, but JavaScript is a scripting language with a very simple syntax! Almost anyone can put small "snippets" of code into their HTML pages. JavaScript can put dynamic text into an HTML page - A JavaScript statement like this: document.write("<h1>" + name + "</h1>") can write a variable text into an 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 an HTML element. JavaScript can read and write HTML elements - A JavaScript can read and change the content of an HTML element.
  3. 3. Java Script What can a JavaScript do? JavaScript can be used to validate data - A JavaScript can be used to validate form data before it is submitted to a 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
  4. 4. Features Java Script  Statement Ends with Semicolon  Handling Old versions of Browers  Case Sensitive  Ignores white space (extra space) • i.e. “computer” and “ computer”  Insert special characters • i.e. document.write(“My name is “James””); •Output:- My name is “James”  Comments: // Single line comments /* multi line comments…. */
  5. 5. Java Script <html> <body> <script type="text/javascript"> document.write("This is my first JavaScript!"); </script> </body> </html>
  6. 6. Java Script <html> <body> <script type="text/javascript"> document.write("<h1>Hello World!</h1>"); </script> </body> </html>
  7. 7. Java Script <html> <body> <H1> <script type="text/javascript"> document.write("Hello World!"); </script> </H1> </body> </html>
  8. 8. Java Script <html> <head> <script type="text/javascript"> document.write(“Head Section Script!"); </script> </head> <body> <script type="text/javascript"> document.write(“Body Section Script!"); </script> </body> </html>
  9. 9. Java Script External Java Script Same script cam be use in several pages Write the script in a separate JavaScript file and store the file with xyz.js extension Use the file in HTML page
  10. 10. Java Script External Java Script //External JavaScript file f1.js document.write(“This is external Script!”);
  11. 11. Java Script External Java Script Use the file in another script <html> <head> <script src=“f1.js"> </script> </head> <body> <script type="text/javascript"> document.write(“Demo of External File!"); </script> </body> </html>
  12. 12. Java Script Variables in Script RULES:  Case Sensitive  Begin with Alphabet Letter or Underscore  Character, digit and Underscore only. i.e. var age = 25; var stud_name = “james thomas”;
  13. 13. Java Script Scope of Variables in Script  Local o variable within the function o lifetime is till the function is in execution  Global o variable outside the function o lifetime is until page closed
  14. 14. Java Script Datatypes in Script Empty  Null  Boolean  Char  Integer  Long  Float  Double  Date  String  Object
  15. 15. Java Script ParseXXX() Method Self Study…
  16. 16. Java Script Operators: 1) Arithmetic 2) Logical 3) Relational 4) Assignment (shorthand) 5) String 6) Bitwise 7) Conditional (Ternary) 8) Special 9) new
  17. 17. Java Script Conditional Statements: 1) if 2) if else 3) Nested if 4) Switch case
  18. 18. Java Script Looping/ Iteration Statements: 1) while 2) Nested while 3) Do… while 4) For 5) Nested for 6) Break 7) Continue
  19. 19. Java Script <html> <head> <script type="text/javascript"> function message() { alert("This alert box was called with the onload event"); } </script> </head> <body onload="message()"> </body> </html>