각도 2 요소 표시 및 숨기기

각도 2 요소 표시 및 숨기기

---

Angular 2의 부울 변수에 따라 요소를 숨기고 표시하는 데 문제가 있습니다.

이것은 div가 표시하고 숨기는 코드입니다.

<div *ngIf="edited==true" class="alert alert-success alert-dismissible fade in" role="alert">
        <strong>List Saved!</strong> Your changes has been saved.
</div>

변수는 "편집"되었으며 내 구성 요소에 저장됩니다.

export class AppComponent implements OnInit{

  (...)
  public edited = false;
  (...)
  saveTodos(): void {
   //show box msg
   this.edited = true;
   //wait 3 Seconds and hide
   setTimeout(function() {
       this.edited = false;
       console.log(this.edited);
   }, 3000);
  }
}

saveTodos 함수가 시작되면 요소가 숨겨 지지만 요소가 표시되지만 3 초 후에 변수가 다시 false로 바뀌더라도 요소가 숨겨지지 않습니다. 왜?

---

* ngIf 지시어를 사용해야합니다

<div *ngIf="edited" class="alert alert-success box-msg" role="alert">
        <strong>List Saved!</strong> Your changes has been saved.
</div>


export class AppComponent implements OnInit{

  (...)
  public edited = false;
  (...)
  saveTodos(): void {
   //show box msg
   this.edited = true;
   //wait 3 Seconds and hide
   setTimeout(function() {
       this.edited = false;
       console.log(this.edited);
   }.bind(this), 3000);
  }
}

---

업데이트 : Timeout 콜백 내에있을 때 외부 범위에 대한 참조가 누락되었습니다.

위의 추가와 같이 .bind (this)를 추가하십시오.

Q : 편집은 전역 변수입니다. * ngFor-loop 내에서 당신의 접근 방식은 무엇입니까? – Blauhirn

A : 반복하는 객체에 속성으로 편집을 추가하고 싶습니다.

<div *ngFor="let obj of listOfObjects" *ngIf="obj.edited" class="alert alert-success box-msg" role="alert">
        <strong>List Saved!</strong> Your changes has been saved.
</div>


export class AppComponent implements OnInit{

  public listOfObjects = [
    {
       name : 'obj - 1',
       edit : false
    },
    {
       name : 'obj - 2',
       edit : false
    },
    {
       name : 'obj - 2',
       edit : false
    } 
  ];
  saveTodos(): void {
   //show box msg
   this.edited = true;
   //wait 3 Seconds and hide
   setTimeout(function() {
       this.edited = false;
       console.log(this.edited);
   }.bind(this), 3000);
  }
}

---

달성하고자하는 것에 따라 두 가지 옵션이 있습니다.

1. You can use the hidden directive to show or hide an element

   <div [hidden]="!edited" class="alert alert-success box-msg" role="alert">
     <strong>List Saved!</strong> Your changes has been saved.
   </div>
   

2. You can use the ngIf control directive to add or remove the element. This is different of the hidden directive because it does not show / hide the element, but it add / remove from the DOM. You can loose unsaved data of the element. It can be the better choice for an edit component that is cancelled.

   <div *ngIf="edited" class="alert alert-success box-msg" role="alert"> 
     <strong>List Saved!</strong> Your changes has been saved.
   </div>
   

For you problem of change after 3 seconds, it can be due to incompatibility with setTimeout. Did you include angular2-polyfills.js library in your page ?

---

When you don't care about removing the Html Dom-Element, use *ngIf.

Otherwise, use this:

<div [style.visibility]="(numberOfUnreadAlerts == 0) ? 'hidden' : 'visible' ">
   COUNTER: {{numberOfUnreadAlerts}} 
</div>

---

For child component to show I was using *ngif="selectedState == 1"

Instead of that I used [hidden]="selectedState!=1"

It worked for me.. loading the child component properly and after hide and un-hide child component was not undefined after using this.

---

This is a good use case for a directive. Something like this is surprisingly useful.

@Directive({selector: '[removeAfter]'}) export class RemoveAfter {
  constructor(readonly element: ElementRef<HTMLElement>) { }

  /**
   * Removes the attributed element after the specified number of milliseconds. 
   * Defaults to (1000)
   */
  @Input() removeAfter = 1000;


  ngOnInit() {
    setTimeout(() => {
      this.element.nativeElement.remove();
    }, this.removeAfter);
  }
}

---

We can do it by using the below code snipet..

Angular Code:

 export class AppComponent {  
    toggoleShowHide:string ="visible";  
 }

Html Template:

  Enter text to hide or show item in bellow: 
  <input type="text" [(ngModel)]="toggoleShowHide">
  <br>
  Toggle Show/hide:
  <div [style.visibility]="toggoleShowHide">   
     Final Release Angular 2!
  </div>

---

Depending on your needs, *ngIf or [ngClass]="{hide_element: item.hidden}" where CSS class hide_element is { display: none; }

*ngIf can cause issues if you're changing state variables *ngIf is removing, in those cases using CSS display: none; is required.

---

@inoabrian solution above worked for me. I ran into a situation where I would refresh my page and my hidden element would reappear on my page. Here's what I did to resolve it.

export class FooterComponent implements OnInit {
public showJoinTodayBtn: boolean = null;

ngOnInit() {
      if (condition is true) {
        this.showJoinTodayBtn = true;
      } else {
        this.showJoinTodayBtn = false;
      }
}

---

Just add bind(this) in your setTimeout function it will start working

setTimeout(function() {
       this.edited = false;
       console.log(this.edited);
   }.bind(this), 3000);

and in HTML change

<div *ngIf="edited==true" class="alert alert-success alert-dismissible fade in" role="alert">
        <strong>List Saved!</strong> Your changes has been saved.
</div>

To

<div *ngIf="edited" class="alert alert-success alert-dismissible fade in" role="alert">
        <strong>List Saved!</strong> Your changes has been saved.
</div>

참고URL : https://stackoverflow.com/questions/35163009/angular-2-show-and-hide-an-element