typescript OnScroll 事件离子 2
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OnScroll event Ionic 2
提问by BA1995
Picking up when a user scroll on Ionic 2 is confusing me. I basically want to say, when a user scrolls down the page, do something.
当用户在 Ionic 2 上滚动时拿起让我很困惑。我基本上想说，当用户向下滚动页面时，做一些事情。
Any examples would be great.
任何例子都会很棒。
UPDATE:
更新：
I have this in my constructor, so when the page scrolls I want to close the keyboard, due to it being left open and no other way to close.
我的构造函数中有这个，所以当页面滚动时我想关闭键盘，因为它保持打开状态并且没有其他方法可以关闭。
import { Component, ViewChild } from '@angular/core';
import { NavController, NavParams, Content } from 'ionic-angular';
import { Keyboard } from '@ionic-native/keyboard';
export class SearchPage {
@ViewChild(Content)
content:Content;
constructor(public keyboard: Keyboard, public formBuilder: FormBuilder, public navCtrl: NavController, public navParams: NavParams, public apiAuthentication: ApiAuthentication, private http: Http) {
this.content.ionScroll.subscribe((data)=>{
this.keyboard.close();
});
}
}
However I get this error Cannot read property 'ionScroll' of undefinedam i putting it in the wrong place?
但是我收到这个错误Cannot read property 'ionScroll' of undefined是我把它放在错误的地方吗？
回答by Erevald
You can subscribe to content events.
您可以订阅内容事件。
Content has 3 output events:
内容有3 个输出事件：
- ionScrollEmitted on every scroll event.
- ionScrollEndEmitted when scrolling ends.
- ionScrollStartEmitted when the scrolling first starts.
- ionScroll在每个滚动事件上发出。
- ionScrollEnd滚动结束时发出。
- ionScrollStart在滚动第一次开始时发出。
Listen to an event:
监听事件：
@ViewChild(Content)
content: Content;
// ...
ngAfterViewInit() {
this.content.ionScrollEnd.subscribe((data)=>{
//... do things
});
}
Or do it from the DOM:
或者从 DOM 执行：
<ion-content (ionScroll)="onScroll($event)">
For Ionic 4
对于离子 4
<ion-content [scrollEvents]="true" (ionScroll)="onScroll($event)">
回答by Mahendra Hirapra
You can use ngOnInit method to register the scroll event :
您可以使用 ngOnInit 方法注册滚动事件：
ngOnInit() {
if (this.content) {
this.content.ionScroll.subscribe((data)=>
this.keyboard.close();
});
}
}
回答by alex351
When inside a custom directive try with something like this:
在自定义指令中尝试使用以下内容：
import { Renderer2 } from '@angular/core';
...
constructor(private renderer: Renderer2) {}
ngOnInit() {
this.renderer.listen(this.myElement, 'scroll', (event) => {
// Do something with 'event'
console.log(this.myElement.scrollTop);
});
}
