Jan's Working with the Web

  Navigating: Errors

Errors occur in web pages with annoying frequency. (It's even more annoying to the web authors than it is to you!)

You can not do much yourself about most of the errors. But it helps to know what is going on. Some error messages leave you totally in the dark.

There are several sources for errors.

1. Author
2. Server
3. Scripting
4. Browser/Version mismatch

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If the browser cannot find the file, you will get an error message, either in a dialog box or in a web page in the browser.

Help the webmaster: If you visit a page and find that a link on the page does not work, an image is missing, or if you experience some other problem with the pages, send a brief, polite email to the webmaster of that site. There is often a link at the site for reporting such problems. It might be in the footer or in the Contact Us page. Report exactly which page has the problem and where on the page. Describe exactly what happened and what you expected to happen. Include the name and version of your browser and operating system that you are using. It does make a difference!

A webmaster may never know that a link is broken unless someone reports it, especially for links to other sites. Politeness works both directions.

Software that automatically checks for broken links can only sense a failed link. It cannot tell that a page or image there but was the wrong one!

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Server Errors

Sending web pages out over the Internet is a complex process. There are many ways for it to go wrong. The server can be so overwhelmed with tasks that it just ignores your browser's request for a web page. This is common with breaking stories on news sites or with videos that have 'gone viral'. That is, they have gotten very popular. Or perhaps the web server is just having a really bad day!

The server can be mis-configured so that parts of the page are not sent out correctly, especially forms, sound, video, or other embedded objects. This is most likely to occur after the technical people fixed a different issue. Fixing one problem sometimes causes another one!

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Scripting Errors

Scripts are small programs that are part of web pages or are attached to them. A script might be written by the web author or it could have been written by someone else.

Uses for scripts:

• Validate your form entries
  Examples: To make sure a typed USA zip code is exactly 5 numbers or that an email address contains an @ and a dot.

• Open a link in a new window; set the size and features of the new window.

• Menus on a web page - change color or size when mouse hovers, expand submenus on click, float above the page to stay in view when the page scrolls, etc.

• Show or hide parts of the page in response to clicking something.

• Many cool and helpful features of interactive web pages.

JavaScript, ASP, Perl, and PHP are languages that are commonly used for scripts affecting web pages.

Unfortunately these scripts are very picky, like any other computer program. A misplaced comma or apostrophe or semicolon can cause complete failure. It can be horrendously difficult to debug a script (find the cause of an error).
[I had trouble with a little script that hides some text and reveals other text when you click a link. It failed in Firefox on one page but worked on another page! I had used the wrong type of brackets in the code. The real mystery is why it worked anywhere at all!]

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Browser/Version Mismatch

The author of an HTML page must sometimes consider what browsers and versions of those browsers their viewers will be using. There are some cool things that the author can have the page do that just don't work in all browsers.

Example: The web page for my faculty email account was designed to work in Internet Explorer. I used Chrome to access that page successfully for quite a while. But one day I tried to download a file that was attached to an email (my direct deposit pay stub!). I got an error message about the file. But the message used the wrong file name and wrong file type. I never found out why that happened and no one would fix the problem. They just told me to use Internet Explorer instead! I did find that if I saved the file anyway and changed its name and extension back to the original, the file would open properly. Tech support did not bother to suggest that. Very annoying! Eventually the function worked correctly in Chrome so something got fixed. Hurrah!

Example: I taught a class that used web-based tests from the textbook's publisher. The testing site would not let me log in except from Internet Explorer 8 or 9, not in earlier versions of IE nor from other browsers.

As Internet Explorer has become less and less popular, we are returning to the days when web authors must think harder about the fancy features that they want to include. Writing pages that use code that meets published standards, currently HTML5, may still not work as intended in all browsers. It's the browsers that are not keeping up!

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