我目前正在尝试将<select>
的onchange
事件绑定到对象方法(用TypeScript编写的JavaScript类(内部的事件处理程序,如下所示:
HTML:
<div id="readerTemplate" data-win-control="WinJS.Binding.Template">
<div>
<select class="win-dropdown"
data-win-control="WinJS.UI.Repeater"
data-win-options="{data: versions}"
data-win-bind="value: version; onchange: versionChangeHandler">
<option data-win-bind="value: fileName; textContent: versionName">
</option>
</select>
<div class="win-type-title" data-win-bind="textContent: version"></div>
</div>
</div>
JS/TypeScript:
loadTabsUI(pivot: WinJS.UI.Pivot) {
for (let tab of this.tabs) {
var tabDiv = document.createElement("div");
var pivotItemDiv = document.createElement("div");
var pivotItem = new WinJS.UI.PivotItem(pivotItemDiv);
pivotItemDiv.setAttribute('data-win-bind', 'winControl.header: title');
var rptrDiv = document.createElement("div");
var rptr = new WinJS.UI.Repeater(rptrDiv, { "data": tab.readers, "template": document.getElementById("readerTemplate").winControl });
pivotItem.contentElement.appendChild(rptrDiv);
pivot.items.push(pivotItem);
WinJS.Binding.processAll(pivotItemDiv, tab);
}
}
正在进行绑定的行:var rptr = new WinJS.UI.Repeater(rptrDiv, { "data": tab.readers, "template": document.getElementById("readerTemplate").winControl });
具有方法的读取器类:
class Reader {
...
...
versionChangeHandler(evt: UIEvent): void {
// goal is to execute the following line:
this.setVersionAsync((evt.target as any).value);
}
...
...
}
当<select>
的选择发生变化时,versionChangeHandler
将被调用。然而,问题是我无法访问函数中正确的this
,这使我无法在正确的对象实例上运行setVersionAsync
,该对象实例是WinJS.UI.Repeater
(在前面JS的绑定中(用来填充/绑定readerTemplate
的对象实例。
关于解决这个问题有什么想法吗?(我在Reader类的构造函数中调用这个WinJS.Utilities.markSupportedForProcessing(this.versionChangeHandler);
,因为否则我会遇到绑定异常。(
谢谢!
然而,问题是我无法在函数中访问正确的this。
这是因为环境发生了变化。您可以使用以下代码来解决此问题:
class Reader {
public handlerProxy: any;
constructor() {
this.handlerProxy = (evt: UIEvent) => { this.versionChangeHandler(evt, this); }
}
...
...
versionChangeHandler(evt: UIEvent,that): void {
// goal is to execute the following line:
that.setVersionAsync((evt.target as any).value);
}
...
...
}
在HTML中将versionChangeHandler
更改为handlerProxy
:
<div id="readerTemplate" data-win-control="WinJS.Binding.Template">
<div>
<select class="win-dropdown"
data-win-control="WinJS.UI.Repeater"
data-win-options="{data: versions}"
<!--here change versionChangeHandler to handlerProxy.-->
data-win-bind="value: version; onchange: handlerProxy">
<option data-win-bind="value: fileName; textContent: versionName">
</option>
</select>
<div class="win-type-title" data-win-bind="textContent: version"></div>