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CS 21A

CS 21A. Beginning JavaScript Programming. Project 1 Integrating JavaScript and HTML. Sonny Huang. Project 1 Integrating JavaScript and HTML. Outline l    Discuss how to integrate JavaScript and HTML l        Insert SCRIPT tags on a Web page l        Write beginning and ending SCRIPT tags

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CS 21A

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  1. CS 21A • Beginning JavaScript Programming Project 1 Integrating JavaScript and HTML Sonny Huang

  2. Project 1 Integrating JavaScript and HTML Outline l   Discuss how to integrate JavaScript and HTML l       Insert SCRIPT tags on a Web page l       Write beginning and ending SCRIPT tags l       Define and use flickering to draw attention l       Describe the background color property of the document object l       Set the background color of a Web page using JavaScript l       Save the HTML file l       Test the Web page l       Discuss JavaScript variables

  3. Project 1 Integrating JavaScript and HTML Outline l       Extract the system date l       Use several variables to construct a message l       Describe the write() method of the document object l       Write a user-defined function that displays a message and links viewers to a new site l       Describe how the setTimeout() method works l       Use the lastModified property to display the last modified document date l       Print an HTML Notepad file

  4. Introduction • Introduction www.bmwusa.com. Advanced features of JavaScript and HTML will be able to combine HTML style sheets and JavaScript to create dynamic pages.

  5. Introduction Electronic commerce(E-commerce) • Conducting business on-line. This includes, for example, marketing, buying and selling products and services with digital cash and via Electronic Data Interchange (EDI). • More about e-commerce: http://www.outsourcing-journal.com/issues/apr1998/insight.html

  6. Introduction Domain Name A name that identifies one or more IP addresses. For example, the domain name microsoft.com represents about a dozen IP addresses. Domain names are used in URLs to identify particular Web pages. For example, in the URL http://www.pcwebopedia.com/index.html, the domain name is pcwebopedia.com. Every domain name has a suffix that indicates which top level domain (TLD) it belongs to. There are only a limited number of such domains.

  7. Introduction . For example: • gov - Government agencies • edu - Educational institutions • org - Organizations (nonprofit) • mil - Military • com - commercial business • net - Network organizations • ca - Canada • th - Thailand Because the Internet is based on IP addresses, not domain names, every Web server requires a Domain Name System (DNS) server to translate domain names into IP addresses.

  8. Introduction JavaScript(Object based language) • Uses built-in objects, but is not capable of creating classes of objects or using inheritance features of object-oriented languages. • Has predefined properties, methods, and event handlers • Object is a person, place, or thing. • Properties are attributes of objects and describe some aspect about the object. • Methods are actions.

  9. Introduction See Page J A.7 in appendix A for a more detail list of objects

  10. Introduction An event is the result of a user’s action. Event handlers are the way to associate that action with the set of JavaScript codes we want to execute. J A.5 in Appendix A for a more detail list of event handlers.

  11. Project One – Fun with Phonics Web Page • Create a web page that will display a message to inform the user that the web site location has been moved. • There will have a link to the new web sit and also, within seconds will generate a alert message to inform the user to transfer to the new location

  12. Project One – Fun with Phonics Web Page An event is the result of a user’s action. Event handlers are the way to associate that action with the set of JavaScript codes we want to execute. J A.5 in Appendix A for a more detail list of event handlers.

  13. Project One – Fun with Phonics Web Page

  14. Project One – Fun with Phonics Web Page <HTML> <HEAD> <TITLE>Fun with Phonics</TITLE> <SCRIPT LANGUAGE="JAVASCRIPT"> <!--Hide from old browsers function chngSite() { alert("You are about to be transported to the new site location!") location = "http://www.scsite.com/" } //--> </SCRIPT> </HEAD>

  15. Project One – Fun with Phonics Web Page <BODY> <CENTER><IMG SRC="fun.jpg" HSPACE=5 VSPACE=5 HEIGHT=64 WIDTH=129></CENTER> <CENTER><HR Width="75%"></CENTER> <SCRIPT LANGUAGE="JAVASCRIPT"> <!--Hide from old browsers document.bgColor="red" document.bgColor="white" document.bgColor="blue" document.bgColor="white" document.bgColor="green" document.bgColor="white" document.bgColor="blanchedalmond"

  16. Project One – Fun with Phonics Web Page var tNow = new Date() var tlocDate = tNow.toLocaleString() var tDate = tlocDate.substring(0,10) document.write("<H2><CENTER>Welcome, today is "+tDate+"</CENTER></H2>") var intro1 = "Hi, thanks for visiting our Web site, but we have moved. Please make a note " var intro2 = "of our new URL (www.funphonics.com) and notify the Webmaster about our new " var intro3 = "location. Click<A Href='http://www.scsite.com/'> here </A> or wait 15 seconds " var intro4 = "to be moved automatically to our new site." var introMsg = intro1+intro2+intro3+intro4

  17. Project One – Fun with Phonics Web Page document.write("<H4><Font Color='firebrick'>"+introMsg+"</H4></FONT>") setTimeout("chngSite()",15000) document.write("<BR><H4><CENTER>This document was last modified "+document.lastModified+"</CENTER></H4>") //--> </SCRIPT> </BODY> </HTML>

  18. Project One – Fun with Phonics Web Page Starting Notepad

  19. Project One – Fun with Phonics Web Page Notepad Window

  20. Project One – Fun with Phonics Web Page Display the .htm files

  21. Project One – Fun with Phonics Web Page Searching the proper folder to locate fun.htm file.

  22. Project One – Fun with Phonics Web Page We will see the contents of the file as follow displayed.

  23. Inserting Script Tags on a Web Page We can place JavaScript code anywhere in the HTML code Common Agreed: 1. User-defined JavaScript functions should place at the HEAD section. • Even handlers or other JavaScript code should place at the BODY section. JavaScript section begins with <SCRIPT> tag and end with </SCRIPT> tag.

  24. Inserting Script Tags on a Web Page Writing the Beginning SCRIPT Tag <SCRIPT LANGUAGE="JAVASCRIPT"> <!--Hide from old browsers Language: to define the version of JavaScript. If it is not defined, the default is JavaScript. HTML comment line: to hide any script language that a browser may not be able to interpret.

  25. Inserting Script Tags on a Web Page Put the JavaScript tag at the BODY section.

  26. Inserting Script Tags on a Web Page Put “<SCRIPT LANGUAGE="JAVASCRIPT"> <!--Hide from old browsers “ codes in the area.

  27. Using a Flicker on a Web Page to Draw Attention Using the changes of background color to capture attentions. BGCOLOR is one of the attribute of <BODY> tag. But the background color can be set only once. JavaScript DOCUMENT object’s BGCOLOR property can be used to change the background color. document.bgColor = value To set the background color to red : document.bgColor="red"

  28. Using a Flicker on a Web Page to Draw Attention Placing several of these statements in sequence will create a flicking effect. document.bgColor="red" document.bgColor="white" document.bgColor="blue" document.bgColor="white" document.bgColor="green" document.bgColor="white" document.bgColor="blanchedalmond"

  29. Using a Flicker on a Web Page to Draw Attention Placing place two of these statements in sequence will create a flicking effect. document.bgColor="red" document.bgColor="white" Closing the comment and SCRIPT tag as follow: //--> </SCRIPT>

  30. Using a Flicker on a Web Page to Draw Attention Closing the comment and SCRIPT tag as follow: //--> </SCRIPT> Save it as a new name funwithphonics.htm.

  31. Using a Flicker on a Web Page to Draw Attention Run with a browser.

  32. Using a Flicker on a Web Page to Draw Attention Put more of of these statements in sequence will create a better flicking effect. document.bgColor="blue" document.bgColor="white" document.bgColor="green" document.bgColor="white" document.bgColor="blanchedalmond“

  33. Using a Flicker on a Web Page to Draw Attention Save the file again, and try it on a browser.

  34. Using a Flicker on a Web Page to Draw Attention The final screen should look like this.

  35. JavaScript Variables var A statement that declares a variable, optionally initializing it to a value. The scope of a variable is the current function or, for variables declared outside a function, the current application. Using var outside a function is optional; you can declare a variable by simply assigning it a value. However, it is good style to use var, and it is necessary in functions if a global variable of the same name exists.

  36. JavaScript Variables Syntax varvarname [= value] [..., varname [= value] ] Arguments varname is the variable name. It can be any legal identifier. value is the initial value of the variable and can be any legal expression.

  37. JavaScript Variables JavaScript variables are case sensitive and follow rules as in following table.

  38. JavaScript Variables • JavaScript is a loosely typed language. That means you do not have to specify the data type of a variable when you declare it, and data types are converted automatically as needed during script execution. • Literals • You use literals to represent values in JavaScript. These are fixed values, not variables, that you literally provide in your script. There are Integers literals (Decimal, Octal, and Hexadecimal), Floating-point literals, Boolean literals (true and false), and String literals( enclosed in double (") or single (') quotation marks.

  39. JavaScript Variables We can declare a variable in two ways: • By simply assigning it a value; for example, x = 42 • With the keyword var; for example, var x = 42 When we set a variable identifier by assignment outside of a function, it is called a global variable, because it is available everywhere in the current document. When we declare a variable within a function, it is called a local variable, because it is available only within the function. Using var is optional, but we need to use it if we want to declare a local variable inside a function that has already been declared as a global variable.

  40. Extracting the System Date JavaScript does not have a date data type. However, you can use the Date object and its methods to work with dates and times in your applications. The Date object has a large number of methods for setting, getting, and manipulating dates. It does not have any properties. JavaScript handles dates similarly to Java. The two languages have many of the same date methods, and both languages store dates as the number of milliseconds since January 1, 1970, 00:00:00.

  41. Extracting the System Date To create a Date object: dateObjectName = new Date([parameters]) where dateObjectName is the name of the Date object being created; it can be a new object or a property of an existing object. The parameters in the preceding syntax can be any of the following: • Nothing: creates today's date and time. For example, today = new Date(). • A string representing a date in the following form: "Month day, year hours:minutes:seconds."

  42. Extracting the System Date For example, Xmas95 = new Date("December 25, 1995 13:30:00"). If you omit hours, minutes, or seconds, the value will be set to zero. • A set of integer values for year, month, and day. For example, Xmas95 = new Date(95,11,25). A set of values for year, month, day, hour, minute, and seconds. For example, Xmas95 = new Date(95,11,25,9,30,0).

  43. Extracting the System Date We can use toLocalString() to convert the un-manipulated date objects to a manipulated data string. And using substring method to abstract the needed information.

  44. Extracting the System Date stringName.substring(indexA, indexB) Parameters stringName is any string or a property of an existing object. indexA is any integer from zero to stringName.length - 1, or a property of an existing object. indexB is any integer from zero to stringName.length, or a property of an existing object. Description Characters in a string are indexed from left to right. The index of the first character is zero, and the index of the last character is stringName.length - 1.

  45. Extracting the System Date • If indexA is less than indexB, the substring method returns the subset starting with the character at indexA and ending with the character before indexB. • If indexA is greater than indexB, the substring method returns the subset starting with the character before indexB and ending with the character at indexA. • If indexA is equal to indexB, the substring method returns the empty string.

  46. Extracting the System Date var tNow = new Date() var tlocDate = tNow.toLocaleString() var tDate = tlocDate.substring(0,10)

  47. Extracting the System Date Start to insert code from the cursor point.

  48. Extracting the System Date Inserting the following codes var tNow = new Date() var tlocDate = tNow.toLocalString() var tDate = tlocDate.substring(0,10)

  49. Extracting the System Date Some methods for Date objects: getDate Method. Returns the day of the month for the specified date. Syntax dateObjectName.getDate() Parameters dateObjectName is either the name of a Date object or a property of an existing object.

  50. Extracting the System Date Description The value returned by getDate is an integer between one and 31. Examples The second statement below assigns the value 25 to the variable day, based on the value of the Date object Xmas95. Xmas95 = new Date("December 25, 1995 23:15:00")day = Xmas95.getDate()

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