问题
I have defined login element as follows:
<polymer-element name="my-login" extends="form">
<template> ...</template>
and dart class as follows:
@CustomTag('my-login')
class MyLogin extends PolymerElement { .... }
In the main application component, I am trying to create my-login as follows:
MyLogin p = new Element.tag("my-login", "FormElement");
This generates exception:
Exception: type 'HtmlElement' is not a subtype of type 'MyLogin' of 'p'.
The code works if "extends=form" is removed from polymer-element declaration :
<polymer-element name="my-login">
and created as follows:
MyLogin p = new Element.tag("my-login");
How to dynamically create custom element that extends other HTML element?
回答1:
You should instantiate it as
Element y = new Element.tag('form', 'my-login');
What seems not to work is
MyLogin y = new Element.tag('form', 'my-login');
this should result in the HTML for the inserted element
<form is="my-login"></form>
回答2:
factory MyLogin() => document.createElement("form", "my-login");
Then you can just call:
MyLogin login = new MyLogin();
This works for me.
来源：https://stackoverflow.com/questions/20474071/dynamically-create-polymer-element