JavaScript Errors and exceptions

1.Error objects

Represents an error that is created and thrown when an error occurs in the code run.

Create Error:
New Error ([Message],[filename],[linenumber])

Error type:

• Evalerror errors related to eval
• Internalerror JavaScript engine internal error, such as too many recursion
• Rangeerror a numeric variable or parameter exceeds the valid range
• Referenceerror Invalid reference
• SyntaxError syntax error
• TypeError variable or parameter is not a valid type
• Invalid argument passed to encodeURI () or decodeURI by Urierror

Error.prototype Main Properties

• Name: ' Error '
• Message error message
• Stack error Tracking

2. Handling Exceptions

The try Catch statement can handle exceptions. There are three types of structures:

• Try Catch
• Try finally
• Try Catch finally

The exception that occurs in try no longer executes the remaining code and executes the catch instead.

1  　　　　　 Try{//statements that need to be executed2Console.log (' Begin ');3             Throw NewError (' hoho! ');4             //throw new Error (' hoho! ', ' test.html ', ' 28 ');5Console.log (' after ');//will not be executed6         }7         Catch(ERR) {//statement executed when there is an exception in try8Console.error (Err.stack);//error:hoho! at test.html:299             //Console.log (err.name+ ":" +err.message); Error:hoho!Ten         } One         finally{//statements that execute regardless of whether or not an exception occurs AConsole.log (' End. ')); -}

When try is nested, the exception is captured one time by the nearest catch. A new exception can be thrown out of the catch. A return in inally will end the entire try and no longer handle the exception.

1  　　　　  Try{2             Try{3                 Throw NewError (' hoho! ');4}Catch(err) {5Console.error (' inner ', err.message);6                 Throwerr;7}finally{8Console.log (' End ');9             }Ten}Catch(err) { OneConsole.error (' outer ', err.message); A         } -         //Output: -         //End the         //Inner hoho! -         //outer hoho!

4. Monitor all exceptions

1 function // parameters take chrome as an example 2 3             Console.log (' Handling error ... '); 4 5             return true;   // true to not prompt for error, flase prompt error 6         }78         //Allert (1);

JavaScript Errors and exceptions