- Home
- Products
- Integration
- Tutorial
- Barcode FAQ
- Purchase
- Company
<!-- // Begin // NOTE:: Replace this line with JavaScript code // End --> in Java
<!-- // Begin // NOTE:: Replace this line with JavaScript code // End --> Create QR In Java Using Barcode maker for Java Control to generate, create QR Code 2d barcode image in Java applications. Quick Response Code Decoder In Java Using Barcode scanner for Java Control to read, scan read, scan image in Java applications. All three of these lines are comments In web programming, a comment is one or more lines of text that is ignored by the browser when interpreting the code Programmers often use comments to make a program easier for humans to read, but in the preceding code, the first and last lines are used to stop browsers that don t support JavaScript from displaying the code As time goes on, this technique becomes less and less important But it is still quite prevalent, and there is really no reason not to include it The <!-- and --> are markers for the start and end of HTML comments JavaScript comments are marked with double slashes (//), which is why the browser will ignore the second line as well Barcode Encoder In Java Using Barcode printer for Java Control to generate, create bar code image in Java applications. Decoding Barcode In Java Using Barcode scanner for Java Control to read, scan read, scan image in Java applications. Communicate with the User
Printing QR Code In Visual C#.NET Using Barcode maker for .NET Control to generate, create QR Code 2d barcode image in Visual Studio .NET applications. Draw QR Code ISO/IEC18004 In VS .NET Using Barcode generator for ASP.NET Control to generate, create QR Code image in ASP.NET applications. Many JavaScript programs perform their tasks quietly A web page may use JavaScript to verify that all the fields on a form have been completed in the proper manner When they are complete, QR Generation In VS .NET Using Barcode creator for .NET framework Control to generate, create QR Code 2d barcode image in .NET applications. QR Code Maker In Visual Basic .NET Using Barcode maker for Visual Studio .NET Control to generate, create QR Code 2d barcode image in Visual Studio .NET applications. How to Do Everything with JavaScript
UPC - 13 Printer In Java Using Barcode creation for Java Control to generate, create EAN / UCC - 13 image in Java applications. ANSI/AIM Code 128 Maker In Java Using Barcode generation for Java Control to generate, create Code 128 Code Set B image in Java applications. the JavaScript program allows the form to be submitted to the web server for further processing But if one of the form fields has not been filled out properly, JavaScript should, ideally, inform the user so that they can correct the problem and submit the form again There are generally two ways to bring an error like this to the user s attention The first is to take advantage of a JavaScript alert box, which requires the user to click an OK button in order for processing to continue This is considered a slightly intrusive technique that ensures the user reads and acknowledges the error message The other way is to write an informative message inside the web page directly This is obviously a less intrusive technique, although you must be sure that the user does not accidentally overlook the message In this section, we will examine how to communicate with the user using both methods, as each will be important before we move on to the next chapter Paint Matrix Barcode In Java Using Barcode printer for Java Control to generate, create 2D Barcode image in Java applications. Print Data Matrix ECC200 In Java Using Barcode drawer for Java Control to generate, create Data Matrix image in Java applications. Display an Alert Message
MSI Plessey Encoder In Java Using Barcode printer for Java Control to generate, create MSI Plessey image in Java applications. Code 3/9 Creation In .NET Using Barcode drawer for VS .NET Control to generate, create Code 39 Extended image in .NET framework applications. JavaScript provides three types of pop-up dialog boxes for use in your applications: Generating UPC-A Supplement 5 In Visual Basic .NET Using Barcode creation for VS .NET Control to generate, create UPC-A Supplement 2 image in .NET framework applications. EAN 13 Generation In None Using Barcode creator for Microsoft Word Control to generate, create EAN-13 image in Office Word applications. An alert box A confirm box A user-input prompt box
DataMatrix Drawer In None Using Barcode creator for Office Word Control to generate, create Data Matrix ECC200 image in Office Word applications. 1D Barcode Generator In C#.NET Using Barcode creation for .NET framework Control to generate, create Linear image in Visual Studio .NET applications. Basic alert messages are displayed using the built-in alert function: Bar Code Creation In Visual Studio .NET Using Barcode printer for ASP.NET Control to generate, create bar code image in ASP.NET applications. EAN13 Reader In Java Using Barcode scanner for Java Control to read, scan read, scan image in Java applications. alert ("This message will be displayed to the browser"); You can place any text string or expression inside the parentheses The dialog box displayed looks like this in Internet Explorer Netscape Navigator displays a similar message box
CHAPTER 1: Prepare to Program in JavaScript
A confirm box acts in much the same way as an alert box, except it displays both OK and Cancel buttons to the user The confirm box tells the program which button the user chose, allowing two different outcomes result = confirm ("Would you like a piece of chocolate cake "); The result variable will contain true if the user selects the OK button, or false otherwise This is how the confirm box appears in Internet Explorer Finally, the user-input prompt box allows the program to ask for a typed response to a message This is rarely used on Internet web pages, as HTML web forms are a more commonly accepted way to retrieve user input firstname = prompt ("What is your first name ", "Enter name here"); The result of this JavaScript code is shown here
Write Text to the Browser Window
Many of the examples in this book will use the documentwrite() function to print text into the web browser window This can be used for more than just error reporting In fact, it is quite common to see web sites using documentwrite() to support dynamic functions such as navigation, user help, banner ad rotation, and more documentwrite ("<b>This text goes right into the browser</b>") How to Do Everything with JavaScript
Notice how you can include HTML tags inside the documentwrite() function and the browser will process those tags By adding a few documentwrite() statements into our HTML template, we can create a web page with a bit more content <html> <head> <title>JavaScript sample code</title> </head> <body> <h1>Hamlet, by Bill Shakespeare</h1> <script language="JavaScript" type="text/javascript"> <!-- // Begin // NOTE:: Replace this line with JavaScript code documentwrite ("To be, or not to be: that is the question:<br>"); documentwrite ("Whether 'tis nobler in the mind to suffer<br>"); documentwrite ("The slings and arrows of outrageous fortune,<br>"); documentwrite ("Or to take arms against a sea of troubles,<br>"); documentwrite ("And by opposing end them<br>"); // End --> </script> </body> </html> As you can see in Figure 1-5, our documentwrite() statements were output to the screen just as if we had entered them directly in HTML This technique becomes more useful when we get into the next chapter, when we learn about variables, functions, and statements Now that we have covered the boring stuff the history of the language, and what it is used for we are ready to jump into a bit of real programming The next chapter starts off by covering the basics of JavaScript, to get you ready to start coding on your own
|
|