Question

我希望尝试下一代＆＃34;下一代＆＃34; Dart JS互操作的目标是能够导出Dart库以供JS使用。但它似乎并不适合我。我跟着README：

https://github.com/dart-lang/js-interop/blob/master/README.md

我创建了一个新项目，将依赖项设置为此github repo，添加了一个类似于自述文件的A类，并尝试使用控制台从javascript实例化A类。

在控制台中使用默认或命名构造函数时，我得到：

var a = new dart.lib.A.withName('word');
TypeError: undefined is not a function
var a = new dart.lib.A();
TypeError: undefined is not a function

这改写功能了吗？难道我做错了什么？是否应该使用js-interop的不同分支？

这是我自述的简单项目：

## pubspec.yaml

name: lib
description: A sample Dart lib published to JS
dependencies:
  browser:
  js:
    git: git://github.com/dart-lang/js-interop.git
transformers:
- js
- js/initializer

## lib/a.dart

library lib;

import 'package:js/js.dart';

@Export()
class A {
  String name;
  A();
  A.withName(this.name);
}

## web/index.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>index</title>
  </head>
  <body>
    <p id="text"></p>
    <script type="application/dart" src="index.dart"></script>
    <!-- for this next line to work, your pubspec.yaml file must have a dependency on 'browser' -->
    <script src="packages/js/interop.js"></script>
    <script src="packages/browser/dart.js"></script>
  </body>
</html>

## web/index.dart

import 'package:lib/a.dart';
import 'package:js/js.dart';

main() {
  initializeJavaScript();
  var a = new A();
}

## Generated index.dart_initialize.js

window.dart = window.dart || {};

window.dart.Object = function DartObject() {
  throw "not allowed";
};

window.dart.Object._wrapDartObject = function(dartObject) {
  var o = Object.create(window.dart.Object.prototype);
  o.__dart_object__ = dartObject;
  return o;
};


// library lib
(function (ns) {
  var lib = ns;
  ["lib"].forEach(function (s) {
    lib = lib[s] = lib[s] || {};
  });

  // class A
  (function(parent) {
    var constructor = parent.A = function _A() {
      this.__dart_object__ = constructor._new();
    };
    constructor.prototype = Object.create(dart.Object.prototype);
    constructor.prototype.constructor = constructor;
    constructor._wrapDartObject = function(dartObject) {
      var o = Object.create(constructor.prototype);
      o.__dart_object__ = dartObject;
      return o;
    };

    constructor.withName = function _withName(name) {
      this.__dart_object__ = constructor._new_withName(name);
    }
    constructor.withName.prototype = constructor.prototype;

  })(lib);
})(window.dart);

Answer 1

我刚试过你的代码，事实上我已经从指令中留下了一些东西。您需要在initializeJavaScript()方法中调用main()来设置导出。此外，interop.js的脚本标记需要在Dart脚本之前。

一旦我做了这些更改，我就可以运行你的代码并在JS控制台中执行此操作：

> var a = new dart.lib.A.withName('word');
< undefined
> a
< _withName {__dart_object__: DartObject, constructor: function}
> a.name
< "word"
> a instanceof dart.lib.A;
< true

Answer 2

这是一项正在进行中的工作。你必须等到使用它之前。

我该如何试用最新的JS互操作？ https://github.com/dart-lang/js-interop

2 个答案: