text: 6: Talking to the Page in Java Generate QR Code in Java 6: Talking to the Page
  6: Talking to the PageQuick Response Code Drawer In JavaUsing Barcode creator for Java Control to generate, create QR-Code image in Java applications.JavaScript segments Sometimes I still print out code in separate blocks, so (as always) try to look at the code in its natural habitat, on either of the companion Web sites (wwwaharrisbooksnet/jad or wwwdummiescom/go/ javascriptandajaxfd) through your browserPrint Barcode In JavaUsing Barcode maker for Java Control to generate, create bar code image in Java applications.Writing JavaScript code to change colors
  Scan Bar Code In JavaUsing Barcode reader for Java Control to read, scan read, scan image in Java applications.The page is pretty simple, but it has a few new features: It has no CSS A form of CSS will be dynamically created through the code The script is in the body I can t place this particular script in the header, because it refers to the body When the browser first sees the script, there must be a body for the text to change If I put the script in the head, there is no body yet when the browser reads the code, so it gets confused If I place the script in the body, then there is a body, so the script can change it (It s really okay if you don t get this nuance at first This is probably the only time you ll see this particular trick, because I ll show a better way in the next example) Use a DOM reference to change the style colors That long trail of breadcrumbs syntax takes you all the way from the document through the body to the style and finally to the color It s tedious but thorough Set the foreground color to white You can change the color property to any valid CSS color value (a color name or a hex value) It s just like CSS, because you are affecting the CSS Set the background color to blue Again, this is just like setting CSSPrint QR Code 2d Barcode In Visual C#.NETUsing Barcode creation for .NET Control to generate, create QR Code ISO/IEC18004 image in VS .NET applications.Managing Button Events
  QR Printer In .NETUsing Barcode generation for .NET Control to generate, create QR Code 2d barcode image in .NET framework applications.Of course, there s no good reason to write code such as bluehtml It s just as easy to build CSS as it is to write JavaScript The advantage comes when you use the DOM dynamically to change the page s behavior after it has finished loading Figure 6-4 shows a page called backgroundColorshtml The page is set up with the default white background color It has two buttons on it, which should change the body s background color Click the blue button, and you ll see that it works, as verified in Figure 6-5Making Quick Response Code In VB.NETUsing Barcode creator for .NET Control to generate, create QR-Code image in .NET applications.Part II: Using JavaScript to Enhance Your Pages
  Drawing Code 3 Of 9 In JavaUsing Barcode encoder for Java Control to generate, create ANSI/AIM Code 39 image in Java applications.Figure 6-4: The page is white with two buttons I ve gotta click blue
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  EAN-13 Creator In JavaUsing Barcode maker for Java Control to generate, create EAN-13 image in Java applications.Again, the color change isn t very convincing in a black-and-white book You should be able to tell from the figures that the color did indeed change, but look on the Web site for real color-changing action Some really exciting things just happened: The page has a form If you need a refresher on form elements, please check out Bonus 1 on either of the companion Web sites (www dummiescom/go/javascriptandajaxfd or wwwaharrisbooks net/jad) The button does something Plain old XHTML forms don t really do anything; you ve got to write some kind of programming code to accomplish that This program does something before your eyes There s a setColor() function The page has a function that takes a color name and applies it to the background style Both buttons pass information to the setColor() function The color name will be passed as a parameter to the setColor() functionGenerating Code128 In JavaUsing Barcode maker for Java Control to generate, create USS Code 128 image in Java applications.Setting up the playground
  Encode EAN128 In Visual C#Using Barcode creation for VS .NET Control to generate, create UCC-128 image in .NET applications.<body> <h1>Click a button to change the color</h1> <form action = > <fieldset> <input type = button value = blue onclick = changeColor( blue ) /> <input type = button value = white onclick = changeColor( white ) /> </fieldset> </form> </body> </html> Most Web pages actually treat the XHTML page as the user interface and the JavaScript as the event-manipulation code that goes underneath It makes sense, then, to look at the HTML code that acts as the playground first It contains a form Note that the form s action attribute is still empty You won t mess with that until you work with the server in 14 The form has a fieldset The input elements need to be inside something, and a fieldset seems like a pretty natural choice The page has two buttons The two buttons on the page are nothing new, but they ve never done anything before The buttons both have onclick attributes This special attribute can accept one line of JavaScript code Usually that line calls a function, as I have done in this program Each button calls the same function, but with a different parameter Both buttons call changeColor(), but one sends the value blue and the other white Presumably, changeColor will change a color That s exactly what it will do In fact, it will change the background color Generally I write the XHTML code first before the script As you can see, the form provides all kinds of useful information that will help me make the script Specifically, it s clear that I need to write a function called changeColor(), this function should take a color name as a parameter, and should change the background to the indicated color With that kind of information established, the function is half-written!UPC - 13 Encoder In VS .NETUsing Barcode generation for .NET Control to generate, create EAN / UCC - 13 image in VS .NET applications.Read Universal Product Code Version A In .NETUsing Barcode recognizer for .NET framework Control to read, scan read, scan image in VS .NET applications.EAN / UCC - 13 Creation In VB.NETUsing Barcode encoder for VS .NET Control to generate, create GTIN - 128 image in .NET applications.Code 128C Creator In Visual Basic .NETUsing Barcode creator for Visual Studio .NET Control to generate, create ANSI/AIM Code 128 image in VS .NET applications.
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