resources/src/mediawiki.base/mediawiki.errorLogger.js

   1 /**
   2  * Try to catch errors in modules which don't do their own error handling.
   3  *
   4  * @class mw.errorLogger
   5  * @singleton
   6  */
   7 ( function () {
   8         'use strict';
   9
  10         mw.errorLogger = {
  11                 /**
  12                  * Fired via mw.track when an error is not handled by local code and is caught by the
  13                  * window.onerror handler.
  14                  *
  15                  * @event global_error
  16                  * @param {string} errorMessage Error errorMessage.
  17                  * @param {string} url URL where error was raised.
  18                  * @param {number} lineNumber Line number where error was raised.
  19                  * @param {number} [columnNumber] Line number where error was raised. Not all browsers
  20                  *   support this.
  21                  * @param {Error|Mixed} [errorObject] The error object. Typically an instance of Error, but anything
  22                  *   (even a primitive value) passed to a throw clause will end up here.
  23                  */
  24
  25                 /**
  26                  * Install a window.onerror handler that will report via mw.track, while preserving
  27                  * any previous handler.
  28                  *
  29                  * @param {Object} window
  30                  */
  31                 installGlobalHandler: function ( window ) {
  32                         // We will preserve the return value of the previous handler. window.onerror works the
  33                         // opposite way than normal event handlers (returning true will prevent the default
  34                         // action, returning false will let the browser handle the error normally, by e.g.
  35                         // logging to the console), so our fallback old handler needs to return false.
  36                         var oldHandler = window.onerror || function () {
  37                                 return false;
  38                         };
  39
  40                         /**
  41                          * Dumb window.onerror handler which forwards the errors via mw.track.
  42                          *
  43                          * @param {string} errorMessage
  44                          * @param {string} url
  45                          * @param {number} lineNumber
  46                          * @param {number} [columnNumber]
  47                          * @param {Error|Mixed} [errorObject]
  48                          * @return {boolean} True to prevent the default action
  49                          * @fires global_error
  50                          */
  51                         window.onerror = function ( errorMessage, url, lineNumber, columnNumber, errorObject ) {
  52                                 mw.track( 'global.error', { errorMessage: errorMessage, url: url,
  53                                         lineNumber: lineNumber, columnNumber: columnNumber, errorObject: errorObject } );
  54                                 return oldHandler.apply( this, arguments );
  55                         };
  56                 }
  57         };
  58
  59         mw.errorLogger.installGlobalHandler( window );
  60 }() );