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Uncaught TypeError when compiling working Dart project to js. #15125

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DartBot opened this issue Nov 17, 2013 · 9 comments
Closed

Uncaught TypeError when compiling working Dart project to js. #15125

DartBot opened this issue Nov 17, 2013 · 9 comments
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closed-obsolete Closed as the reported issue is no longer relevant type-bug Incorrect behavior (everything from a crash to more subtle misbehavior)

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@DartBot
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DartBot commented Nov 17, 2013

This issue was originally filed by cyrill.zadr...@gmail.com

What steps will reproduce the problem?

  1. Attached MpisMobile project runs fine in DartVm
  2. Build project (compile to javascript)
  3. Run mpismobile.html with browser

What is the expected output? What do you see instead?
It should show a map with default location in zurich. Map stays grey and in browser console following error is shown:

Uncaught TypeError: Cannot call method 'get$map' of null mpismobile.html_bootstrap.dart.js:142561

What version of the product are you using? On what operating system?

Dart Editor version 1.0.0_r30187 (DEV)
Dart SDK version 1.0.0.3_r30187
Chrome 31
Firefox 25
IE 10

Please provide any additional information below.
Dart project example can be also found on https://github.com/thomasfrick1/mpis/tree/dart2js-problem/MpisMobile

Attachment:
MpisMobile.zip (5.07 MB)
@DartBot
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DartBot commented Nov 19, 2013

This comment was originally written by michael.haubenwa...@gmail.com

This might be some timing problem with querySelector.

I had the same problem and after moving the script element with the compiled JS from HEAD to the bottom of the document BODY it worked for me again.

@DartBot
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DartBot commented Nov 20, 2013

This comment was originally written by michael.haubenwa...@gmail.com

When compiling the sample content for a dart web application, this comes up in the resulting JS file:

TypedData_ListMixin_FixedLengthListMixin: {"": "TypedData_ListMixin+FixedLengthListMixin;", $asList: null}}],
["", "webappsample.dart", , R, {
main: function() {
  var t1, t2;
  t1 = document.querySelector("#sample_text_id");
  t1.textContent = "Click me!";
  t1.toString;
  t1 = new W._ElementEventStreamImpl(t1, C.EventStreamProvider_click._eventType, false);
  H.setRuntimeTypeInfo(t1, [null]);
  t2 = new W._EventStreamSubscription(0, t1._target, t1._eventType, W._wrapZone(R.reverseText$closure), t1._useCapture);
  H.setRuntimeTypeInfo(t2, [H.getRuntimeTypeArgument(t1, "_EventStream", 0)]);
  t2._tryResume$0();
},

reverseText: function($event) {
  var text, buffer, i, t1;
  text = document.querySelector("#sample_text_id").textContent;
  buffer = P.StringBuffer$("");
  for (i = text.length - 1; i >= 0; --i) {
    t1 = text[i];
    buffer._contents = buffer._contents + t1;
  }
  document.querySelector("#sample_text_id").textContent = buffer._contents;
}},
1],
]);

Question is, if "t1.toString;" is used to test for a null/unassigned value of "t1" or is just test output and not removed from the compiler?

@sethladd
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Added Area-Dart2JS, Triaged labels.

@peter-ahe-google
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Pete: I believe that dart2js is doing the right thing by executing main before the rest of the DOM is parsed (leading to querySelector returning null).

Michael: re #­3, yes dart2js will insert t1.toString to check for null. But in this case it seems redundant (as it is preceded by t1.textContent).

Set owner to @blois.

@blois
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blois commented Nov 21, 2013

Correct- the execution is occurring in the head.

The proper fix would be to modify mpismobile.html to move the Dart script to the end of the body tag.

I just opened 15229 against Polymer build- it should either be adding a defer attribute to the generated JS script, or it should add a warning when the script is not at the end of the body (or both).

Added AsDesigned label.

@DartBot
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DartBot commented Nov 21, 2013

This comment was originally written by cyrill....@gmail.com

Thanks for looking into this issue. I just tried out your described workaround and moved <script type="application/dart" src="mpismobile.dart"></script> to the bottom of mpismobile.html.

Tried it with following to examples.

<html>
  ....
  <mpis-maps id="myMap"></mpis-maps>
  
  <script type="application/dart" src="mpismobile.dart"></script>
 
</body>
</html>

or

<html>
  ....
  <mpis-maps id="myMap"></mpis-maps>
  
  <script src="packages/browser/interop.js"></script>
  <script src="http://maps.googleapis.com/maps/api/js?sensor=false">&lt;/script>
  <script type="application/dart" src="mpismobile.dart"></script>
  <script src="packages/browser/dart.js"></script>
  
</body>

In both cases I get this js error.

[10:50:36.800] : NoSuchMethodError : method not found: 'Symbol("map")'
Receiver: Instance of 'UnknownElement'
Arguments: [] @­ file:///C:/dev/projects/eth/mpis/MpisMobile/build/mpismobile.html_bootstrap.dart.js:3894

It's a different error .. so shall I open a different issue here? Or post my problem somewhere else?

@peter-ahe-google
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cc @blois.
cc @rakudrama.
Removed the owner.
Added Triaged label.

@peter-ahe-google
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I've filed issue #15236 regarding the redundant null check.

This was referenced Jun 3, 2015
Closed
Closed
@kevmoo kevmoo added type-bug Incorrect behavior (everything from a crash to more subtle misbehavior) and removed priority-unassigned labels Feb 29, 2016
@matanlurey
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PolymerDart is deprecated.

@matanlurey matanlurey added closed-obsolete Closed as the reported issue is no longer relevant and removed web-dart2js labels Jun 22, 2018
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@sethladd @kevmoo @matanlurey @blois @peter-ahe-google @DartBot