构建Chrome扩展程序时，Dartium和dart2js之间的区别 [英] Difference between Dartium and dart2js when building chrome extensions

问题描述

当我运行 dart2js 编译版本的chrome扩展时遇到以下问题：

  Uncaught TypeError：Object＃< JsObject>没有方法'其中$ 1'
  

我创建了一个最小示例：

background.dart

  import dart：js'; 
 
 void main（）{
 print（main（）...）; 
 context ['js_list'] = new JsObject.jsify（[aaa，bbb]）; 
} 
  

popup.dart

< pre class =lang-dart prettyprint-override> import'dart：js';

var backgroundPage = context [chrome] [extension]。callMethod（getBackgroundPage，[]）;

void main（）{
print（main（）：...）;
testJsList（backgroundPage ['js_list']）;
}

testJsList（List< String> jsList）{
print（testJsList（）：jsList = $ jsList）;
print（testJsList（）：['aaa'，'bbb'] = $ {new JsObject.jsify（['aaa'，'bbb']）
jsList.where（（e）=> e ==bbb）。forEach（print）;
}


在Chromium（Da​​rtium）上运行时：

  main（）：... 
 testJsList（）：jsList = [aaa，bbb] 
 testJsList （）：['aaa'，'bbb'] = [aaa，bbb] 
 bbb 
  

在Chrome上运行时（dart2js - > V8）：

  main 。
 testJsList（）：jsList = aaa，bbb 
 testJsList（）：['aaa'，'bbb'] = [aaa，bbb] 
 Uncaught TypeError：Object＃< JsObject>没有方法'where $ 1'
  

显然，Dart VM正在处理JS Interop与编译的javascript略有不同。 jsList 以不同的方式打印，第二种情况是jsList的错误类型。

---

更新：
看起来这个问题是由三方组件{dart：js，dart2js，chrome API}引起的，因为adhoc创建的JsObject在两个Dartium和dart2js场景。

解决方案

Dartium和dart2js都有自己单独的dart：js实现，行为相同。在这种情况下，它看起来像dart2js实现中的一个错误，因为 JsObject.jsify 应该返回一个 JsArray 实现 List ，但是错误说明它返回一个简单的 JsObject 。

您可以在dartbug.com提交错误吗？

I have the following problem when running dart2js compiled version of my chrome extension:

Uncaught TypeError: Object #<JsObject> has no method 'where$1'

I have created a minimal example:

background.dart

import 'dart:js';

void main() {
  print("main()...");
  context['js_list'] = new JsObject.jsify(["aaa", "bbb"]);
}

popup.dart

import 'dart:js';

var backgroundPage = context["chrome"]["extension"].callMethod("getBackgroundPage", []);

void main() {
  print("main():...");
  testJsList(backgroundPage['js_list']);
}

testJsList(List<String> jsList) {
  print("testJsList(): jsList = $jsList");
  print("testJsList(): ['aaa', 'bbb'] = ${new JsObject.jsify(['aaa', 'bbb'])}");
  jsList.where((e) => e == "bbb").forEach(print);
}

When running on Chromium (Dartium):

main():...
testJsList(): jsList = [aaa, bbb]
testJsList(): ['aaa', 'bbb'] = [aaa, bbb]
bbb

When running on Chrome (dart2js -> V8):

main():...
testJsList(): jsList = aaa,bbb
testJsList(): ['aaa', 'bbb'] = [aaa, bbb]
Uncaught TypeError: Object #<JsObject> has no method 'where$1'

Obviously Dart VM is treating JS Interop slightly differently from a compiled javascript. The jsList is printed differently, and in the second case is ´jsList´ of a "wrong" type.

---

Update: It looks that the problem is caused by the trio {dart:js, dart2js, chrome API} since the adhoc created JsObject is working properly in both Dartium and dart2js scenario.

解决方案

Dartium and dart2js each have their own separate implementation of dart:js, but they're supposed to behave the same. In this case it looks like a bug in the dart2js implementation, because JsObject.jsify is supposed to return a JsArray which implements List, but the error states that it's returning a plain JsObject instead.

Can you file a bug at dartbug.com ?

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