我的dart:js上下文调用在编译为javascript的dart2js后会出现严重问题。
这是我创建的一个简单程序，包括两个文件:
main.dart
import 'dart:html';
import 'dart:js';
calledBack() async {
querySelector('#output3').text = 'Called from JS';
}
void main() {
querySelector('#output1').text = 'Started Dart';
context['callMeFromJS'] = calledBack;
context['app'].callMethod('callMeFromDart');
}
main.js
var App = function() {
};
App.prototype = {
callMeFromDart: function(){
var div = document.getElementById('output2');
div.innerHTML = 'Called from Dart';
callMeFromJS();
}
};
var app = new App();
index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="scaffolded-by" content="https://github.com/google/stagehand">
<title>untitled1</title>
<link rel="stylesheet" href="styles.css">
<script async src="main.dart" type="application/dart"></script>
<script async src="packages/browser/dart.js"></script>
<script src="main.js"></script>
</head>
<body>
<div id="output1"></div>
<div id="output2"></div>
<div id="output3"></div>
</body>
</html>
当我使用Dartium运行它时，它能够按预期的工作。然而，如果我将其编译为JS并在Chromium中打开，有时只能正常工作50%左右的时间。其它时候，我会遇到以下错误：
Uncaught TypeError: Cannot set property 'textContent' of
nulldart.main @ html_dart2js.dart:40598dart._IsolateContext.eval$1 @ isolate_helper.dart:460dart.startRootIsolate @ isolate_helper.dart:122(anonymous function) @ main.dart.js:7141(anonymous function) @ main.dart.js:7142init.currentScript @ main.dart.js:7122(anonymous function) @ main.dart.js:7133(anonymous function) @ main.dart.js:7145
我还有一个更大的项目，出现了类似的错误。这里的错误是以下内容：
Uncaught Uncaught Error: NullError: method not found: 'constructor' on null
Stack Trace:
TypeError: Cannot read property 'constructor' of undefined
at J.T (https://test-download-starsky.gamblify.com/web_game_builds/xmas/xmas_0.0.1-73-ga6a6de0/web/main.dart.js:8103:23)
at $Y (https://test-download-starsky.gamblify.com/web_game_builds/xmas/xmas_0.0.1-73-ga6a6de0/web/main.dart.js:6053:3)
at yS.a (https://test-download-starsky.gamblify.com/web_game_builds/xmas/xmas_0.0.1-73-ga6a6de0/web/main.dart.js:1411:65)
at yS.dart.yS.$1 (https://test-download-starsky.gamblify.com/web_game_builds/xmas/xmas_0.0.1-73-ga6a6de0/web/main.dart.js:1794:22)
at R8.dart.R8.FI (https://test-download-starsky.gamblify.com/web_game_builds/xmas/xmas_0.0.1-73-ga6a6de0/web/main.dart.js:3082:42)
at rq.dart.rq.$0 (https://test-download-starsky.gamblify.com/web_game_builds/xmas/xmas_0.0.1-73-ga6a6de0/web/main.dart.js:2583:21)
at dart.vs.static.HZ (https://test-download-starsky.gamblify.com/web_game_builds/xmas/xmas_0.0.1-73-ga6a6de0/web/main.dart.js:2537:40)
at vs.dart.vs.X2 (https://test-download-starsky.gamblify.com/web_game_builds/xmas/xmas_0.0.1-73-ga6a6de0/web/main.dart.js:2474:3)
at eX.dart.eX.$0 (https://test-download-starsky.gamblify.com/web_game_builds/xmas/xmas_0.0.1-73-ga6a6de0/web/main.dart.js:2576:22)
at OM.dart.OM.Ki (https://test-download-starsky.gamblify.com/web_game_builds/xmas/xmas_0.0.1-73-ga6a6de0/web/main.dart.js:2658:29)