Introduction to javascript.ppt
- 1. Introduction and Operators in Javascript by Mrs. B.Arulmozhi, M.Sc., B.Ed., M.Phil., SET., NET., Assistant Professor and Head, Department of Computer Science and Applications D.K.M. College for Women, Vellore
- 2. Objective Main objective of this powerpoint, to focus about the following points. ï What is Script? ï Some Scripting lanugages. ï Uses of script tag ï About Javascript ï How to add javascript ï Operators in Javascript
- 3. Script ï A scripting or script language is a programming language for a special run-time environment that automates the execution of tasks; the tasks could alternatively be executed one-by-one by a human operator. Scripting languages are often interpreted, rather than compileds ï JavaScript, PHP, Python, VBScript. ï Applications of Scripting Languages : ï 1. To automate certain tasks in a program ï 2. Extracting information from a data set ï 3. Less code intensive as compared to traditional programming languages
- 4. Uses of <Script> tag ï The <script> tag in HTML is used to define the client-side script. ï The <script> tag contains the scripting statements, or it points to an external script file. ï The JavaScript is mainly used in form validation, dynamic changes of content, image manipulation, etc.
- 5. Syntax Syntax: <script> Script Contents... </script> Attributes ï Attributes: Many attribute associated with script tag. ï async: It is used to specify the script is executed asynchronously. ï charset: It is used to specify the character encoding used in an external script file. ï defer: It is used to specify that the script is executed when the page has finished parsing. ï src: It is used to specify the URL of an external script file. ï type: It is used to specify the media type of the script.
- 6. How to add Javascript <html> <body> <script language = "javascript" type = "text/javascript"> <!-- document.write("Hello World!") //--> </script> </body> </html>
- 7. Advantage of Javascript ï Speed. ï Simplicity ï Popularity ï Interoperability ï Server Load ï Rich interfaces ï Extended Functionality. ï Versatility ï Updates
- 8. DISADVANTAGES OF JAVASCRIPT ï Client-Side Security. Because the code executes on the usersâ computer, in some cases it can be exploited for malicious purposes. This is one reason some people choose to disable Javascript. ï Browser Support. JavaScript is sometimes interpreted differently by different browsers. Whereas server-side scripts will always produce the same output, client-side scripts can be a little unpredictable.
- 9. ï Whitespace and Line Breaks ï JavaScript ignores spaces, tabs, and newlines that appear in JavaScript programs. ï Semicolons are Optional ï Simple statements in JavaScript are generally followed by a semicolon character, just as they are in C, C++, and Java. JavaScript, however, allows you to omit this semicolon if each of your statements are placed on a separate line.
- 10. Case Sensitivity ï JavaScript is a case-sensitive language. This means that the language keywords, variables, function names, and any other identifiers must always be typed with a consistent capitalization of letters.
- 11. Data types ï JavaScript allows you to work with primitive data types â ï Numbers, eg. 123, 120.50 etc. ï Strings of text e.g. "This text string" etc. ï Boolean e.g. true or false. ï Null ï Undefined
- 12. Variables ï , JavaScript has variables. Variables can be thought of as named containers. You can place data into these containers and then refer to the data simply by naming the container.
- 13. How to declare variables <script type = "text/javascript"> <!-- var money, name; //--> </script>
- 14. Initializing Variables <script type = "text/javascript"> <!-- var name = "Ali"; var money; money = 2000.50; //--> </script>
- 15. Operators ï Arithmetic Operators (+,-,*,/.%) ï Comparison Operators ï Logical (or Relational) Operators ï Assignment Operators ï Conditional (or ternary) Operators
- 16. Arithmetic Operators S.No. Arithmetic Operator & Description 1 + (Addition)Adds two operandsEx: A + B will give 30 2 - (Subtraction)Subtracts the second operand from the first Ex: A - B will give -10 3 * (Multiplication)Multiply both operands Ex: A * B will give 200 4 / (Division)Divide the numerator by the denominator Ex: B / A will give 2 5 % (Modulus)Outputs the remainder of an integer division Ex: B % A will give 0 6 ++ (Increment)Increases an integer value by one Ex: A++ will give 11 7 -- (Decrement)Decreases an integer value by one Ex: A-- will give 9
- 17. <html> <body> <script type = "text/javascript"> var a = 33; var b = 10; var c = "Test"; var linebreak = "<br />"; document.write("a + b = "); result = a + b; document.write(result);</script></body> </html>
- 18. Arithmetic Operators Comparison /Relational Operator & Description 1 = = (Equal) Checks if the value of two operands are equal or not, if yes, then the condition becomes true. Ex: (A == B) is not true. 2 != (Not Equal) Checks if the value of two operands are equal or not, if the values are not equal, then the condition becomes true. Ex: (A != B) is true. 3 > (Greater than) Checks if the value of the left operand is greater than the value of the right operand, if yes, then the condition becomes true. Ex: (A > B) is not true. 4 < (Less than) Checks if the value of the left operand is less than the value of the right operand, if yes, then the condition becomes true. Ex: (A < B) is true. 5 >= (Greater than or Equal to) Checks if the value of the left operand is greater than or equal to the value of the right operand, if yes, then the condition becomes true. Ex: (A >= B) is not true. 6 <= (Less than or Equal to) Checks if the value of the left operand is less than or equal to the value of the right operand, if yes, then the condition becomes true. Ex: (A <= B) is true.