Quick Note: Favor $exceptionHandler() Over $log.error() In AngularJS
This is just a really minor note. I was looking through some AngularJS code the other day and came across someone using a try-catch block that passed the error off to the $log.error() method. While this works - it logs the error to the console - it doesn't add as much value as the $exceptionHandler() service. There are times when logging to the console makes sense; but, as a general rule, I would try to favor the $exceptionHandler() service over the $log.error() method in the vast majority of cases.
| <!doctype html> | |
| <html ng-app="Demo"> | |
| <head> | |
| <meta charset="utf-8" /> | |
| <title> | |
| Quick Note: Favor $exceptionHandler() Over $log.error() In AngularJS | |
| </title> | |
| </head> | |
| <body ng-controller="AppController"> | |
| <h1> | |
| Quick Note: Favor $exceptionHandler() Over $log.error() In AngularJS | |
| </h1> | |
| <p> | |
| <em>View the console</em>. | |
| </p> | |
| <!-- Load scripts. --> | |
| <script type="text/javascript" src="../../vendor/angularjs/angular-1.4.2.min.js"></script> | |
| <script type="text/javascript"> | |
| // I control the root of the application. | |
| angular.module( "Demo", [] ).controller( | |
| "AppController", | |
| function provideAppController( $scope, $log, $exceptionHandler ) { | |
| // ** Avoid. ** | |
| // -- | |
| // Using the $log.error() method will safely log the error to the console | |
| // if it is available. If the console is not available, the error will | |
| // just be swallowed quietly. | |
| try { | |
| throw( new Error( "Something went boom.")) | |
| } catch ( error ) { | |
| $log.error( error ); | |
| } | |
| // ** Recommended. ** | |
| // -- | |
| // By default, the $exceptionHandler() service does the same thing as | |
| // $log. The default implementation actually just turns around and calls | |
| // $log.error() internally. However, the entire framework defers to the | |
| // $exceptionHandler() for all try / catch blocks which makes it a | |
| // perfect place to track errors. By favoring $exceptionHandler() over | |
| // the $log.error() method, you keep in alignment with the rest of the | |
| // code and make your errors more readily available. | |
| try { | |
| throw( new Error( "Something went boom.")) | |
| } catch ( error ) { | |
| $exceptionHandler( error ); | |
| } | |
| } | |
| ); | |
| </script> | |
| </body> | |
| </html> |
Out of the box, the default implementation of the $exceptionHandler() service just turns around and calls the $log.error() method. So, you get console-logging for free. The real benefit of the $exceptionHandler() service, however, is two fold: For starters, the rest of the framework uses $exceptionHandler() to manage errors. So, by using the $exceptionHandler() service, you are keeping your code more consistent with the rest of the code (and consistency is always a win).
But, the real benefit of using $exceptionHandler() is that you are passing your error through to a service that has become the de-facto point of override for error logging in the AngularJS community. In my apps, I use the $exceptionHandler() service to gather stack-traces (using Stacktrace.js) and to pass those errors off to New Relic for more aggregated tracking. And, I'm not the only one - a similar approach is also outlined in John Papa's AngularJS Style Guide.
So, long-story-short, favor the $exceptionHandler() unless you truly want to log something without the potentiality of it being logged in a more meaningful way.
Want to use code from this post? Check out the license.
Reader Comments