The lack of standardization is the bane of a web developer's life. One can be driven to pulling their hair out trying to remember the differences between browsers and version of browsers. Like everyone else, I'd like not to have to remember all these things or struggle to figure out why a web application doesn't work in one browser but does in others.

Frameworks go along way toward eliminating the problem. The code provided includes tests and branching to handle the idiosyncrasies of browsers—most of the time. There are, however, benefits to testing in several browsers even when they aren't supported browsers. When code fails in one browser, it can help you clean up mistakes that are ignored other browsers. I was reminded of this just the other day.

I was asked to determine why a mouse-out event didn't work in Safari when it worked in IE and Firefox. A tool tip opened as intended but failed to close. Other tool tips on the page worked correctly.

The project uses the Dojo framework and Dojo.byId function to get a reference to the element. Like many such functions provided in other frameworks, it tests whether a string or an object reference is passed. If a string, then getElementById is called and the object reference returned; otherwise, the object reference passed is returned. However, browsers handle loading, parsing, and rendering the page differently.

IE creates a global variable that contains a reference for every DOM element that has an ID with the same name as the ID. As it turns out, Firefox does the same for image tags, and this particular event was on an image tag. I seem to remember older versions of Firefox following IE for all elements but providing a warning in the error console.

It took testing in Safari to discover that the argument intended to be a ID was missing quotes. IE and Firefox converted it to an object reference—one that was not formally declared. It can be argued that this piece of code should have failed in all browsers, but that is another issue.

Testing code in different browsers helps make your code cleaner because is it is more likely errors will be detected.

There are other times browsers handle coding errors or fail to handle them. For example, IE doesn't handle trailing commas in object literals. Can you think of any other coding mistakes that some browsers ignore?

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