My Talk at

1. Handle with care
Fehlerbehandlung in JavaScript
Friday 8 November 13

2. WER BIN ICH?
•
Sebastian Springer
•
https://github.com/sspringer82
•
@basti_springer
Friday 8 November 13

3. Friday 8 November 13

4. Was ist ein Fehler?
☠
Friday 8 November 13

5. Was ist ein Fehler?
☠
Whoops, this should not happen.
Friday 8 November 13

6. Fehlertypen
Friday 8 November 13

7. Fehlertypen
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8. Fehlertypen
Friday 8 November 13

9. Fehlertypen
Friday 8 November 13

10. Fehlertypen
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11. Fehlertypen
Friday 8 November 13

12. Eigene Fehler
throw new Error('An error occurred');
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13. Eigene Fehler
var MyErr = function (message) {
this.message = message;
this.name = 'MyErr';
}
MyErr.prototype = new Error();
MyErr.prototype.constructor = MyErr;
Friday 8 November 13

14. Friday 8 November 13

15. Abfangen von Fehlern
try {
throw new Error('Hello World');
} catch (e) {
console.log(e);
} finally {
console.log('Finished');
}
Friday 8 November 13

16. Abfangen von Fehlern
try {
} catch (RangeError e) {
}
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17. Abfangen von Fehlern
try {
} catch (RangeError e) {
}
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18. Abfangen von Fehlern
try {
} catch (e) {
if (e instanceof RangeError) {
}
}
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19. Callbacks
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20. Fehler in Callbacks
Applikation
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Asynchrone
Ausführung

21. Fehler in Callbacks
Applikation
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Asynchrone
Ausführung

22. Fehler in Callbacks
Asynchrone
Ausführung
Applikation
Operation
Friday 8 November 13

23. Fehler in Callbacks
Asynchrone
Ausführung
Applikation
Operation
Friday 8 November 13

24. Fehler in Callbacks
Asynchrone
Ausführung
Applikation
Operation
☠☂ ☏☣☢
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25. Fehler in Callbacks
Asynchrone
Ausführung
Applikation
Operation
Callback
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☠☂ ☏☣☢

26. Fehler in Callbacks
Asynchrone
Ausführung
Applikation
Operation
Callback
Friday 8 November 13
☠☂ ☏☣☢

27. Fehler in Callbacks
function myTimeout() {
throw new Error("whoops");
}
Friday 8 November 13

28. Fehler in Callbacks
function myTimeout() {
throw new Error("whoops");
}
try {
setTimeout("myTimeout()", 0);
} catch (e) {
console.log(e);
}
Friday 8 November 13

29. Fehler in Callbacks
☠
function myTimeout() {
throw new Error("whoops");
}
try {
setTimeout("myTimeout()", 0);
} catch (e) {
console.log(e);
}
Friday 8 November 13

30. Friday 8 November 13

31. Fehler in Callbacks
$.ajax({
url: ‘/something’,
success: function (data) {
...
},
error: function (data) {
...
}
});
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32. Friday 8 November 13

33. Fehler in Callbacks
var fs = require('fs');
fs.readFile('file', function (err, d) {
...
});
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34. Fehler in Callbacks
var fs = require('fs');
fs.readFile('file', function (err, d) {
...
});
null
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35. Fehler in Callbacks
Error {
errno: ...
code: ...
path: ...
message: ...
}
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36. Events
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37. Error Events
Subject
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Observer

38. Error Events
Subject
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Observer

39. Error Events
Subject
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Observer

40. Error Events
Subject
Observer
on(‘error’, function...
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41. Error Events
Subject
Observer
on(‘error’, function...
☠☂ ☏☣☢
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42. Error Events
Subject
Observer
on(‘error’, function...
☠☂ ☏☣☢
trigger(‘error’, {...
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43. Error Events
Subject
Observer
on(‘error’, function...
☠☂ ☏☣☢
trigger(‘error’, {...
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44. Promises
http://wiki.commonjs.org/wiki/Promises
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45. Promises
In Javascript, promises are objects which represent the pending result of
an asynchronous operation.
(Martin Fowler)
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46. Promises
$.ajax({
url: ‘/my/url’
}).done(function (data) {
...
}).fail(function (data) {
...
}).always(function (data) {
...
});
Friday 8 November 13

47. Promises
function promisedFunc() {
var def = $.Deferred();
// do something asynchronous
// success
def.resolve();
// fail
def.reject();
return def.promise();
}
Friday 8 November 13

48. Promises
promisedFunc().done(function () {
// success
}).fail(function () {
// failure
}).always(function () {
// success & failure
});
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49. Promises
$.when(
promisedFunc(),
promisedFunc()
).then(success, failure);
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50. Promises
•
http://api.jquery.com/category/deferred-object/
Client only
•
https://github.com/kriskowal/q
Client + Server
•
https://github.com/kriszyp/node-promise
Server only
Friday 8 November 13

51. Node.js Domain
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52. Node domain
var domain = require(‘domain’).create();
domain.on(‘error’, function (err) {
console.log(err);
});
domain.run(function () {
...
});
Friday 8 November 13

53. Node Domain
Wird ausgeführt bei:
•
•
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error-Events
Exceptions

54. window.onerror
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55. window.onerror
catch it all!
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56. window.onerror
window.onerror = function (msg, url, nr)
{
...
return true;
}
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57. window.onerror
window.onerror
Code
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58. und jetzt?
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59. und jetzt?
Logging FTW!
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60. Logging
Client
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Server

61. Logging
Client
Server
☠☂ ☏☣☢
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62. Logging
Log Message
Client
☠☂ ☏☣☢
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Server

63. Logging
Log Message
Client
☠☂ ☏☣☢
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Server

64. Logging
window.onerror = function (msg, url, nr)
{
$.ajax({
url: ‘/logger’
data: {
msg: msg,
url: url,
nr: nr
}
});
return true;
}
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65. Logging
Fire and Forget
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66. Fragen?
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67. Sebastian Springer
sebastian.springer@mayflower.de
Mayflower GmbH
Mannhardtstr. 6
80538 München
Deutschland
@basti_springer
https://github.com/sspringer82
Friday 8 November 13