Javascript 如何创建自定义属性以添加if.bind?
我想创建一个属性来显示或隐藏基于某些全局状态的元素 例如:Javascript 如何创建自定义属性以添加if.bind?,javascript,attributes,aurelia,Javascript,Attributes,Aurelia,我想创建一个属性来显示或隐藏基于某些全局状态的元素 例如: <div state='new,unknown'>yadayadayada</div> yadayada 然后,该属性将div元素转换为: <div if.bind="['new','unknown'] | state & signal : 'state-change'">...</div> 。。。 状态值转换器将数组转换为布尔值 目标是,如果当前全局状态是提供的任何状态,
<div state='new,unknown'>yadayadayada</div>
yadayada
然后,该属性将div元素转换为:
<div if.bind="['new','unknown'] | state & signal : 'state-change'">...</div>
。。。
状态值转换器将数组转换为布尔值
目标是,如果当前全局状态是提供的任何状态,则显示元素,否则隐藏它
我不想要包含compose的自定义元素。您可以创建一个属性,并将
if
绑定到该属性。像这样:
import {computedFrom} from 'aurelia-framework';
export class MyViewModel {
@computedFrom('something', 'someOtherValue')
get globalState() {
//do all conditions you need
if (myArray.indexOf('something') != -1 && someOtherValue) {
return true;
}
return false;
}
}
那么您只需绑定:
<div if.bind="globalState"></div>
Aurelia备忘单上有。我根据它构思了一个解决方案。唯一的区别是:
- 计算显示或隐藏的逻辑(当然)
- 也订阅全局状态,而不仅仅是
valueChanged
或者然后我必须在我想要使用全局状态的每个模型中导入全局状态。因此,这不是我的首选解决方案。我不确定自定义属性是否可以模拟
if.bind
,因为当它触发时,元素已经附加到DOMYourGistRun
链接已失效。
import {BoundViewFactory, ViewSlot, customAttribute, templateController, inject} from 'aurelia-framework';
import {BindingEngine} from 'aurelia-binding';
import {State} from './state';
@customAttribute('naive-if')
@templateController
@inject(BoundViewFactory, ViewSlot, BindingEngine, State)
export class NaiveIf {
constructor(viewFactory, viewSlot, bindingEngine, state) {
this.show = false;
this.viewFactory = viewFactory;
this.viewSlot = viewSlot;
this.bindingEngine = bindingEngine;
this.state = state;
}
bind() {
this.updateView();
this.subscription = this.bindingEngine.propertyObserver(this.state, 'value')
.subscribe((newValue, oldValue) => this.updateView());
}
unbind() {
if (this.subscription) this.subscription.dispose();
}
valueChanged(newValue) {
this.updateView();
}
updateView() {
let isShowing = this.show;
let showStates = this.value.split(',');
this.show = showStates.indexOf(this.state.value) != -1;
if (this.show && !isShowing) {
let view = this.viewFactory.create();
this.viewSlot.add(view);
} else if (!this.show && isShowing) {
this.viewSlot.removeAll();
}
}
}