Merge pull request #4225 from atom/bo-error-events

Add onWillThrowError

package.json

@@ -95,7 +95,7 @@
     "keybinding-resolver": "0.20.0",
     "link": "0.26.0",
     "markdown-preview": "0.110.0",
-    "metrics": "0.38.0",
+    "metrics": "0.39.0",
     "open-on-github": "0.30.0",
     "package-generator": "0.32.0",
     "release-notes": "0.36.0",

spec/atom-spec.coffee

@@ -52,3 +52,72 @@ describe "the `atom` global", ->
     it 'loads the default core config', ->
       expect(atom.config.get('core.excludeVcsIgnoredPaths')).toBe true
       expect(atom.config.get('editor.showInvisibles')).toBe false
+
+  describe "window onerror handler", ->
+    beforeEach ->
+      spyOn atom, 'openDevTools'
+      spyOn atom, 'executeJavaScriptInDevTools'
+
+    it "will open the dev tools when an error is triggered", ->
+      try
+        a + 1
+      catch e
+        window.onerror.call(window, e.toString(), 'abc', 2, 3, e)
+
+      expect(atom.openDevTools).toHaveBeenCalled()
+      expect(atom.executeJavaScriptInDevTools).toHaveBeenCalled()
+
+    describe "::onWillThrowError", ->
+      willThrowSpy = null
+      beforeEach ->
+        willThrowSpy = jasmine.createSpy()
+
+      it "is called when there is an error", ->
+        error = null
+        atom.onWillThrowError(willThrowSpy)
+        try
+          a + 1
+        catch e
+          error = e
+          window.onerror.call(window, e.toString(), 'abc', 2, 3, e)
+
+        delete willThrowSpy.mostRecentCall.args[0].preventDefault
+        expect(willThrowSpy).toHaveBeenCalledWith
+          message: error.toString()
+          url: 'abc'
+          line: 2
+          column: 3
+          originalError: error
+
+      it "will not show the devtools when preventDefault() is called", ->
+        willThrowSpy.andCallFake (errorObject) -> errorObject.preventDefault()
+        atom.onWillThrowError(willThrowSpy)
+
+        try
+          a + 1
+        catch e
+          window.onerror.call(window, e.toString(), 'abc', 2, 3, e)
+
+        expect(willThrowSpy).toHaveBeenCalled()
+        expect(atom.openDevTools).not.toHaveBeenCalled()
+        expect(atom.executeJavaScriptInDevTools).not.toHaveBeenCalled()
+
+    describe "::onDidThrowError", ->
+      didThrowSpy = null
+      beforeEach ->
+        didThrowSpy = jasmine.createSpy()
+
+      it "is called when there is an error", ->
+        error = null
+        atom.onDidThrowError(didThrowSpy)
+        try
+          a + 1
+        catch e
+          error = e
+          window.onerror.call(window, e.toString(), 'abc', 2, 3, e)
+        expect(didThrowSpy).toHaveBeenCalledWith
+          message: error.toString()
+          url: 'abc'
+          line: 2
+          column: 3
+          originalError: error

src/atom.coffee

@@ -173,11 +173,21 @@ class Atom extends Model
       require('grim').deprecate = ->
 
     window.onerror = =>
-      @openDevTools()
-      @executeJavaScriptInDevTools('InspectorFrontendAPI.showConsole()')
       @lastUncaughtError = Array::slice.call(arguments)
+      [message, url, line, column, originalError] = @lastUncaughtError
+      eventObject = {message, url, line, column, originalError}
+
+      openDevTools = true
+      eventObject.preventDefault = -> openDevTools = false
+
+      @emitter.emit 'will-throw-error', eventObject
+
+      if openDevTools
+        @openDevTools()
+        @executeJavaScriptInDevTools('InspectorFrontendAPI.showConsole()')
+
       @emit 'uncaught-error', arguments...
-      @emitter.emit 'did-throw-error', arguments...
+      @emitter.emit 'did-throw-error', {message, url, line, column, originalError}
 
     @unsubscribe()
     @setBodyPlatformClass()
@@ -248,10 +258,31 @@ class Atom extends Model
   onDidBeep: (callback) ->
     @emitter.on 'did-beep', callback
 
+  # Extended: Invoke the given callback when there is an unhandled error, but
+  # before the devtools pop open
+  #
+  # * `callback` {Function} to be called whenever there is an unhandled error
+  #   * `event` {Object}
+  #     * `originalError` {Object} the original error object
+  #     * `message` {String} the original error object
+  #     * `url` {String} Url to the file where the error originated.
+  #     * `line` {Number}
+  #     * `column` {Number}
+  #     * `preventDefault` {Function} call this to avoid popping up the dev tools.
+  #
+  # Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
+  onWillThrowError: (callback) ->
+    @emitter.on 'will-throw-error', callback
+
   # Extended: Invoke the given callback whenever there is an unhandled error.
   #
   # * `callback` {Function} to be called whenever there is an unhandled error
-  #   * `errorMessage` {String}
+  #   * `event` {Object}
+  #     * `originalError` {Object} the original error object
+  #     * `message` {String} the original error object
+  #     * `url` {String} Url to the file where the error originated.
+  #     * `line` {Number}
+  #     * `column` {Number}
   #
   # Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
   onDidThrowError: (callback) ->