我正在尝试更改使用聚合物库的默认Web应用程序,以便创建聚合物元素并将其从DART代码添加到DOM,而不是包含在HTML中.我已成功将元素添加到DOM中,但我的可观察变量未在DOM上更新.事件正在被解雇,价值正在发生变化.我已经使用Observable.dirtyCheck()更新了DOM,但是,这显然很昂贵,所以我试图弄清楚如何在没有dirtyCheck()的情况下让聚合物更新dom.
所以,简而言之,我如何摆脱Observable.dirtyCheck()???
dynamiccreate.dart
library dynamiccreate;
import 'dart:html';
import 'package:polymer/polymer.dart';
main() {
initPolymer();
//create click-counter element at runtime from DART,not HTML
var NewElement = new Element.tag('click-counter');
NewElement.setAttribute("count","5");
//Add to DOM
querySelector('#sample_container_id').children.add(NewElement);
}
dynamiccreate.html
<!DOCTYPE html>
<html>
<head>
<Meta charset="utf-8">
<title>Sample app</title>
<link rel="stylesheet" href="dynamiccreate.css">
<!-- import the click-counter -->
<link rel="import" href="clickcounter.html">
<!-- <script type="application/dart">export 'package:polymer/init.dart';</script> -->
<script src="packages/browser/dart.js"></script>
</head>
<body>
<h1>DynamicCreate</h1>
<p>Hello world from Dart!</p>
<div id="sample_container_id">
<!-- <click-counter count="5"></click-counter> -->
</div>
<script src="dynamiccreate.dart" type="application/dart"></script>
</body>
</html>
clickcounter.dart
import 'package:polymer/polymer.dart';
/**
* A Polymer click counter element.
*/
@CustomTag('click-counter')
class ClickCounter extends PolymerElement {
@published int count = 0;
ClickCounter.created() : super.created() {
}
//increment gets called when dynamically adding object at runtime
//But does not update count on DOM
void increment() {
count++;
//Have to add this to update count in DOM
Observable.dirtyCheck(); //<<<---How do I get rid of this???
}
}
clickcounter.html
<polymer-element name="click-counter" attributes="count">
<template>
<style>
div {
font-size: 24pt;
text-align: center;
margin-top: 140px;
}
button {
font-size: 24pt;
margin-bottom: 20px;
}
</style>
<div>
<button on-click="{{increment}}">Click me</button><br>
<span>(click count: {{count}})</span>
</div>
</template>
<script type="application/dart" src="clickcounter.dart"></script>
</polymer-element>
解决方法
将dynamiccreate.dart文件更改为如下所示,计数器开始在UI中递增：
library dynamiccreate;
import 'dart:html';
import 'package:polymer/polymer.dart';
main() {
initPolymer().run(() {
var newElement = new Element.tag('click-counter');
newElement.setAttribute("count","15");
querySelector('#sample_container_id').children.add(newElement);
});
}
Nit：将变量命名为newElement,而不是NewElement.固定在这里.
