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JAVASCRIPT HOW TO PROGRAM -2

Learn about implementing and maintaining scripts, from requirement analysis to user-defined functions and global variables.

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JAVASCRIPT HOW TO PROGRAM -2

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  1. JAVASCRIPTHOW TO PROGRAM -2 DR. JOHN P. ABRAHAM UTPA

  2. Script development process • Requirement analysis • Goal – Audience • Design • Sketch the page – Site map – outline content - pseudocode • Implementation • Coding • Support & maintenance

  3. Script statements in head • User defined functions • Global variables • Statements that preload images for use in rollover effects

  4. Keep an HTML outline <HTML> <head> <title> Array example </title> <script language ="javaScript"> </script> </head> <body> </body> </HTML>

  5. InputBox <HTML> <head> <title> Ask user name </title> <script language ="javaScript"> var visitor = prompt("What is your name?", " ") </script> </head> <body> </body> </HTML>

  6. Using input <HTML> <head> <title> Ask user name </title> <script language ="javaScript"> var visitor = prompt("What is your name?", “Default Name ") </script> </head> <body> <script language ="javascript"> document.write("<h1> Hello, ", visitor, "! </h1>") </script> </body> </HTML>

  7. Onload (event) <HTML> <head> <title> Ask user name </title> <script language ="javaScript"> var visitor = prompt("What is your name?", " ") </script> </head> <body onLoad="alert('Welcome! '+visitor)"> </body> </HTML>

  8. Alert Box with 2 lines <HTML> <head> <title> Ask user name </title> <script language ="javaScript"> var visitor = prompt("What is your name?", " ") </script> </head> <body onLoad="alert('Welcome! \n'+visitor)"> </body> </HTML>

  9. Function with return value <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>

  10. Looping <HTML> <head> <title> Nested Loop </title> <script language ="javaScript"> var i=1, j; while (i <= 12) {document.writeln("<br>Table for ",i, "<br>"); for (j=1; j <=16; j++) document.writeln(i, " x ", j, " = ", i*j,"<br>"); i++ } </script> </head> <body> </body> </HTML>

  11. Table •  table is divided into rows (with the <tr> tag), • each row is divided into data cells (with the <td> tag). td stands for "table data," and holds the content of a data cell. A <td> tag can contain text, links, images, lists, forms, other tables, etc.

  12. Looping & Table <HTML> <head> <title> Nested Loop </title> <script language ="javaScript"> var i=1, j; while (i <= 12) {document.writeln("<table border='1'>"); document.writeln("<br><tr><td>Table for ",i, "</td></tr>"); for (j=1; j <=16; j++) document.writeln("<tr><td>",i, " x ", j, " = ", i*j,"</td></tr>"); document.writeln("</table>"); i++ } </script> </head> <body> </body> </HTML>

  13. Assignment Help <HTML> <HEAD> <TITLE>Future value of an investment</TITLE> <SCRIPT LANGUATE = "JavaScript"> var age, initial, deposit, rate; getdata(); if (rate >1) rate = rate/100; //convert rate to fraction just in case. document.writeln( age," ", initial," ", deposit," ", rate); function getdata() { document.writeln("<BR> This program calculates your total assets at retirment (age 65)"); document.writeln("<BR> given initial deposit, amount of deposit every 30 days, "); document.writeln("<BR> interest rate and your current age."); document.writeln("<BR>---------------------- data entry ---------------------------<BR>"); age=parseInt(window.prompt("How old are you (must be below 65)?----------------> ")); initial=parseFloat(window.prompt( "What is your initial deposit?----------------------> ")); deposit=parseFloat(window.prompt( "Amount you agree to deposit every 30 days?---------> ")); rate=parseFloat(window.prompt( "What would be your expectation of interest or growth? ")); return initial, deposit, rate, age; } </Script> </HEAD> </HTML>

  14. JavaScript Arrays Dr. John P. Abraham Professor UTPA

  15. Declaring & populating an Array var students = new array() students[0] = “Harry” students[2]= “Jim” var months= new Array(“Jan”,”Feb”…”Dec”) --display— For (i=0; I <= 12; i++) {document.write(i, “. “,months[i], <br>’)

  16. Stack Operations var stack = new Array(); function createStack(top) {top = 0; } function destroyStack(top) {top = 0; } function emptyStack(top ) { return (top = 0); } function push(element) {top = top + 1; stack[top] = element; } function pop() {element = stack[top]; top = top - 1; return element; }

  17. Parsing a String probLen = problem.length; while (j <= probLen-1) { onechar = problem.charAt(j); while ((onechar !=" ") && (j <=probLen-1)) { parse(); j++; onechar = problem.charAt(j); }//while inner if (nums != "") pushStack() else if (opcode != "") domath(); j++; }//while outer

  18. Function parse function parse() { if (onechar >= "." && onechar <= "9") {if (onechar != "/") nums = nums + onechar; else opcode = onechar; } else opcode = onechar; }

  19. Forms and Form Processing (CGI) Dr. John P. Abraham UTPA

  20. Purpose of forms • Collect information for the users (user input collection) • Sent from browsers (clients) to servers

  21. Sample form <form method="post" action="mailto:jabraham@utpa.edu"> Name: <input type="text" size="10" maxlength="40" name="name"> <br /> Password: <input type="password" size="10" maxlength="10" name="password"><br /> <INPUT type="radio" name="sex" value="Male"> Male<BR> <INPUT type="radio" name="sex" value="Female"> Female<BR> <input type="submit" value="Send"> </form>

  22. What is a form • Form element of HTML • Designed to collect input • Mail to vs. server-side scripts • mailto URL causes the form data to sent to an email address. • No server-side scripting is required. • Server-side scripts. CGI, Perl, PHP, ASP, ColdFusion. • Can write the data to a database.

  23. Post vs. Get • Post method – form data is sent separately from the actual call to the server-side script. (data is sent under separate cover) • Preferred method • Get method: the data is appended to the end of the URL that calls a server-side script. • Easy to see what is being sent.

  24. Input types • Text • Selections – • radio buttons • Check boxes • Pull-down menus (pick one for State) • Hidden input elements (such as session info)

  25. Introduction to CGI • Data sent to server require customized processing on the server side. • Common Gateway Interface governs the way a web-server (Apache, IIS, etc.) interacts with an external program. • A popular scripting language conforms to CGI is PERL. • CGI programs can be written any language.

  26. Browsers and CGI • End user clicks the submit button • Form’s data are sent over the internet to the web server. • Web server upon receipt of the requests executes the correct application program • Forwards the input data to that program • The application program performs requested steps. • Generates output back to the server in HTML • Web server forwards the output to the client • Client browser displays it

  27. Outline of a CGI program • Determines request method (get or post) and receives input data. • Decodes and checks input data. • Performs tasks • Produces output in HTML format

  28. Perl programming language • Practical Extension and Reporting Language • 1987 Larry Wall at NASA • Free • Provides a CGI interface module • Portable application (runs on web servers on different platforms)

  29. CGI-tutorial • http://www.cgi101.com/book/ch1/text.html

  30. Example of a CGI program #!/usr/bin/perl print "Content-type: text/html\n\n"; print "<html><head><title>Hello World</title></head>\n"; print "<body>\n"; print "<h2>Hello, world!</h2>\n"; print "</body></html>\n";

  31. HTML5 • It is time for you (and me) to learn HTML5 • I suggest you go to this site and follow the tutorial. http://w3schools.com/html/html5_intro.asp

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