Try... catch is a very practical and safe method for capturing errors. The usage is as follows. Example reference:Http://www.cnblogs.com/newblue/archive/2006/12/28/606100.html <HTML>
<Head> <title> try... catch... finally </title> <Body>
<SCRIPT type = "text/JavaScript">
// <! [CDATA [ // In JavaScript, try... catch can be used for exception handling. For example: Try {
Foo. Bar ();
} Catch (e ){
Alert (E. Name + ":" + E. Message );
}
// Currently, the possible system exceptions include the following 6 types:
// Evalerror: raised when an error occurs executing code in eval ()
// Rangeerror: raised when a numeric variable or parameter is outside of its valid range
// Referenceerror: raised when de-referencing an invalid reference
// Syntaxerror: raised when a syntax error occurs while parsing code in eval ()
// Typeerror: raised when a variable or parameter is not a valid type
// Urierror: raised when encodeuri () or decodeuri () are passed invalid Parameters
// The preceding six exception objects are inherited from error objects. They both support the following two constructor methods:
// New error ();
// New error ("exception information ");
// The method for manually throwing an exception is as follows:
Try {
Throw new error ("whoops! ");
} Catch (e ){
Alert (E. Name + ":" + E. Message );
}
// To determine the type of exception information, you can make a judgment in catch:
Try {
Foo. Bar ();
} Catch (e ){
If (E instanceof evalerror ){
Alert (E. Name + ":" + E. Message );
} Else if (E instanceof rangeerror ){
Alert (E. Name + ":" + E. Message );
}
// Etc
} // Error has the following attributes: // Description: Error description (ie only ).
// Filename: the file name with an error (available only for Mozilla ).
// Linenumber: number of lines in the error (available only for Mozilla ).
// Message: error message (Description in IE)
// Name: Error type.
// Number: Error Code (ie only available ).
// Stack: Error stack information similar to the stack trace in Java (available only by Mozilla ).
// To better understand the error information, you can change the catch part to the following format:
Try {
Foo. Bar ();
} Catch (e ){
If (browsertype! = Browser_ie ){
Alert (
"Name:" + E. Name +
"/Nmessage:" + E. Message +
"/Nlinenumber:" + E. linenumber +
"/Nfilename:" + E. filename +
"/Nstack:" + E. Stack );
}
Else {
Alert (
"Name:" + E. Name +
"/Nerrornumber:" + (E. Number & 0 xFFFF) +
"/Nmessage:" + E. Message ");
}
}
// The throw command in javascript can actually throw any object, and we can accept this object in catch. For example: Try {
Throw new date (); // throw the current time object
} Catch (e ){
Alert (E. tolocalestring (); // display the current time in local format
} //]>
</SCRIPT>
</Body>
</Html> // Exception handling test in different browsers <HTML>
<Head> <title> try... catch... finally </title> <Body>
<SCRIPT type = "text/JavaScript">
// <! [CDATA [ // Exception handling test in different browsers // Firefox3
// Message: foo is not defined; filename:File: // D:/test/test_apply_call.html; Linenumber: 10; Stack: @ file: // D:/test/test_apply_call.html: 10; Name: referenceerror; // IE7
// Name: typeerror; message: 'foo' undefined; number:-2146823279; Description: 'foo' undefined;
Try {
Foo. Bar ();
} Catch (e ){ VaR S = '';
For (I in E)
{ S + = I + ":" + E [I] + ";";
}
Document. Write (s );
} //]>
</SCRIPT>
</Body>
</Html> |
