当JsObject.callMethod工作时，JsFunction.apply不起作用（dart）

I have this often, that JsFunction.apply doesn't work like I would expect. Consider this example:

我经常这样，JsFunction.apply不能像我期望的那样工作。考虑这个例子：

import "dart:js";
import "dart:html";

void main() {
  var div = querySelector('div');
  var span = new SpanElement()..text = "hello world";
  var js = new JsObject.fromBrowserObject(div);
  js["appendChild"].apply([span]);

  // this one does work:
  // js.callMethod("appendChild", [span]);
}

I would expect that js["appendChild"].apply([span]); to work exactly the same as js.callMethod("appendChild", [span]);.

我希望js [“appendChild”]。apply（[span]）;与js.callMethod完全相同（“appendChild”，[span]）;.

另请参见此演示：https：//dartpad.dartlang.org/0f35d76a3c61ba1371f1

1 个解决方案

#1

It works with js["appendChild"].apply([span], thisArg: js);

它适用于js [“appendChild”]。apply（[span]，thisArg：js）;

If you don't provide thisArg it's like you call Function.prototype.apply with null as first argument.

如果你不提供thisArg，就像调用Function.prototype.apply一样，将null作为第一个参数。

Thus your Dart call is the same as the js :

因此你的Dart调用与js相同：

var div = document.querySelector('div');
var span = document.createElement("span");
span.innerText = "hello world";
div["appendChild"].apply(null, [span]);

The execution of above js code leads to a TypeError: Illegal invocation. To make it work you have to use div["appendChild"].apply(div, [span]);.

上面的js代码的执行导致TypeError：非法调用。要使它工作，你必须使用div [“appendChild”]。apply（div，[span]）;.

So it was not a Dart issue but rather a js issue.

所以这不是Dart问题，而是js问题。

#1