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