Internet and Web Technologies
Collecting exercises done during the module.
The purpose of this laboratory session is to help you learn about JavaScript. You will be asked to write 3 small JavaScript programs which generate HTML. In each case the program should be embedded in an HTML page, so that it can be executed by a web browser.
Your HTML page might initially look like the following (which you can copy and paste into a file):
<html>
<head>
<title> ... </title>
</head>
<body>
<script type="text/javascript">
...
</script>
</body>
</html>
Having a script in the body will work for parts 1 and 3 below, but for part 2 (and possibly part 3) you might need a script in the head. I suggest that you place your files in your personal DCS web space (this will be essential for part 3 below). Instructions on how to do this and what the resulting URLs will look like are given on the student web page wiki entry.
Debugging JavaScript can be a painful process. However, Firefox, Chrome and IE now provide debuggers under their "Web developer" or "Tools" menus. For example, with the Firefox debugger you can set breakpoints and then inspect the values of variables at those points.
The three tasks are as follows:
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Write a JavaScript program which will prompt the user (using
window.prompt) for two integer values and will output the larger of the two values using the following HTML:<p>The larger of ?? and ?? is ??</p>with
??replaced by the appropriate values. The values entered by the user are assumed to be strings, so you will need to use theparseIntfunction to convert each value into an integer necessary for the comparison to return correct results. You may find this slide helpful. -
Now modify your program so that the user enters the two values using a form. When the user clicks a button in the form, a function
larger(x, y), which returns the larger of 2 values, is called. This function should be defined in theheadof your HTML page. You may find this slide and the one which follows it helpful. -
First save a copy of the file
pods98.xmlin the same directory (folder) in your web space where you are creating your HTML files. Now write a JavaScript program which will read the file and write eachauthorname as a separate paragraph in the HTML document being displayed. You may find this slide and this one helpful.
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Write a stylesheet to extract the value of the
nameelement which is a child of theproceedingselement in the XML document. The output should be in HTML with the value of thenameelement being the contents of anh1heading. -
Modify the stylesheet in (1) to extract, in addition, the titles of papers presented at the symposium. Each paper title should be inserted inside double quote marks and should constitute a separate paragraph in the HTML, after the
h1heading. -
Write a stylesheet to extract the authors, titles and page numbers of papers presented at the symposium. The output should be in HTML, each paper should constitute a separate paragraph, with the author names listed on one line f ollowed by commas, followed on the next line by the title emphasized and inside double quote marks, followed by a comma and then the characters "pp." (excluding the quotes) and the page numbers followed by a full-stop.
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Now modify the stylesheet in (3) so that it produces a list of all the authors' names before the list of papers (where the authors' names also appear). This might be the first step in producing a stylesheet where the list of authors provides a hyperlinked index to authors' papers. Each author's name should be on a separate line. Do not worry about trying to remove duplicate names.
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Create the XML file:
- Choose a directory in which you will create the XML file, which should have an extension of
.xml. - Use a text editor, such as Textpad, to enter information in XML which conforms to the specification of the application (do not worry about the DTD yet). For the first example, you should represent all the information using elements rather than attributes (for the second, you are free to use attributes too). You should include enough sample data to demonstrate each of different structures which are allowed by the specification. Remember to include the XML declaration at the beginning of the file.
- Choose a directory in which you will create the XML file, which should have an extension of
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Check that the XML file is well-formed:
- Open the file you created in (1) using a browser to check that it is well-formed (the browser will give an error if it is not).
- Modify the file until it is well-formed.
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Create the DTD:
- Now modify the XML file created in (1) to include an internal DTD for documents of the type you have designed, trying to ensure that the XML representation you created is valid with respect to this DTD.
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Validate the XML file:
- Go to the page for the W3C Markup validation Service. You can upload your file to the service for validation. The results of the validation will be presented on a separate page. (Don't worry if you receive a warning about a missing
charsetattribute.) - Modify your XML file until it is valid.
- Go to the page for the W3C Markup validation Service. You can upload your file to the service for validation. The results of the validation will be presented on a separate page. (Don't worry if you receive a warning about a missing
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Invalidate the XML file:
- If you produced a valid XML document straight away or only had to correct a couple of mistakes, now modify your file in ways that you believe make it invalid and check that you understand the error messages returned by the validation service.