Being Verbose - JavaScript

Now, what you just saw was a very primitive exception handler, albeit one which isn't very useful on a production site. Ideally, you'd want the message generated by the exception handler to be a little more descriptive, and to contain some information on the source of the error.

JavaScript satisfies this requirement via two special, pre-defined properties of the Error object generated by an exception - the "name" and "message" properties. Take a look:

<script language="JavaScript">

try {

colours[2] = "red";

} catch (e) {

alert("An exception occurred in the script. Error name: " + e.name 
+ ". Error message: " + e.message); }
</script> 

Here's the output:

Don't want to use the alert() box because it's disruptive and annoying? Write the output directly to the page itself with the writeln() method instead, as below:

It's also possible to write an exception handler to ignore all errors generated in your script - the following example demonstrates:

<script language="JavaScript">

try {

// generate an error

eval("some gibberish") 

} catch (e) {

// ignore it

}
</script>

In this case, it doesn't matter what type of exception JavaScript generates
- the generic handler will catch it, ignore it and continue to process the rest of the script.

It should be noted, however, that this approach, although extremely simple, is *not* recommended for general use. It is poor programming practice to trap all errors, regardless of type, and ignore them; it is far better - and more professional - to anticipate the likely errors ahead of time, and use the "try-catch" construct to isolate and resolve them.