Display one element in Angular 2 while concealing the rest

Question

Display one element in Angular 2 while concealing the rest

Problem:

I am facing an issue with my accordion containing 4 elements. When I click on the first element, it displays not only its content but also the content of the other 3 elements.

Expected Solution:

I want to be able to click on a specific element and have only that element's content displayed while hiding the content of the other elements.

Code Snippet:

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'app-sabias-que',
  templateUrl: './sabias-que.component.html',
  styleUrls: ['./sabias-que.component.scss']
})
export class SabiasQueComponent implements OnInit {

  private _isOpen : boolean = false;
  private tips : Array<any> = [
    {
      heading: 'Title 1',
      content: 'Content to be displayed'
    },
    ...
  ]

  closeOthers(openGroup): void {
    this.tips.forEach((tip) => {
      if (tip !== openGroup) {
        tip.isOpen = false;
      }
    });
  }

  set isOpen(value: boolean) {
    debugger;
    this._isOpen = value;
    if (value) {
      this.closeOthers(this);
    }
  }

  get isOpen() {
    return this._isOpen;
  }

  constructor() { }

  ngOnInit() {
  }

  showContent(): void {
    this.isOpen = !this.isOpen;
  }

}

HTML Code:

<ul class="tips-list">
  <li *ngFor="let tip of tips">
    <h3 class="tips-list__title" 
        [ngClass]="{'tips-list__title--active' : isOpen}" (click)="showContent()">
        {{ tip.heading }}    
    </h3>
    <p class="tips-list__answer" [hidden]="!isOpen">
      {{ tip.content }}  
    </p>
  </li>
</ul>

If you can provide an explanation or code example, it would help me understand how to resolve this issue. I am familiar with jQuery and vanilla JS, but struggling with the concept of using 'this'.

angular typescript

Answer 1

Answer №1

Within all the methods mentioned, the context of this pertains to the component (which is an instance of SabiasQueComponent), rather than to each individual tip.

There exist various potential solutions, with one particular suggestion outlined below.

View demo plunker here

Template:

<ul class="tips-list">
  <li *ngFor="let tip of tips">
    <h3 class="tips-list__title" 
        [ngClass]="{'tips-list__title--active' : tip.isOpen}" (click)="showContent(tip)">
        {{ tip.heading }}    
    </h3>
    <p class="tips-list__answer" [hidden]="!tip.isOpen">
      {{ tip.content }}  
    </p>
  </li>
</ul>

Note the three modifications: changing from

"{'tips-list__title--active' : isOpen}"

to

"{'tips-list__title--active' : tip.isOpen}"

, (click)="showContent()" to (click)="showContent(tip)", and [hidden]="!isOpen"> to [hidden]="!tip.isOpen">. Essentially, we are now accessing the properties specific to each tip instead of pulling them from the component.

Component:

export class SabiasQueComponent implements OnInit {

  private _isOpen : boolean = false;
  private tips : Array<any> = [
    // content remains the same
  ]

  closeAllTips(): void {
    this.tips.forEach((tip) => {
      tip.isOpen = false;
    });
  }

  showContent(tip) {
    if (!tip.isOpen) {
      this.closeAllTips();
    }
    tip.isOpen = !tip.isOpen;
  }

  constructor() { }

  ngOnInit() {
  }

}

In the component's code, showContent() has been updated to accept a tip whose content will be displayed. The get isOpen() and set isOpen() have been removed since it now belongs as a property of each individual tip. Additionally, closeOthers(openGroup) was replaced by the new function closeAllTips().

Answer 2

Within all the methods mentioned, the context of this pertains to the component (which is an instance of SabiasQueComponent), rather than to each individual tip.

There exist various potential solutions, with one particular suggestion outlined below.

View demo plunker here

Template:

<ul class="tips-list">
  <li *ngFor="let tip of tips">
    <h3 class="tips-list__title" 
        [ngClass]="{'tips-list__title--active' : tip.isOpen}" (click)="showContent(tip)">
        {{ tip.heading }}    
    </h3>
    <p class="tips-list__answer" [hidden]="!tip.isOpen">
      {{ tip.content }}  
    </p>
  </li>
</ul>

Note the three modifications: changing from

"{'tips-list__title--active' : isOpen}"

to

"{'tips-list__title--active' : tip.isOpen}"

, (click)="showContent()" to (click)="showContent(tip)", and [hidden]="!isOpen"> to [hidden]="!tip.isOpen">. Essentially, we are now accessing the properties specific to each tip instead of pulling them from the component.

Component:

export class SabiasQueComponent implements OnInit {

  private _isOpen : boolean = false;
  private tips : Array<any> = [
    // content remains the same
  ]

  closeAllTips(): void {
    this.tips.forEach((tip) => {
      tip.isOpen = false;
    });
  }

  showContent(tip) {
    if (!tip.isOpen) {
      this.closeAllTips();
    }
    tip.isOpen = !tip.isOpen;
  }

  constructor() { }

  ngOnInit() {
  }

}

In the component's code, showContent() has been updated to accept a tip whose content will be displayed. The get isOpen() and set isOpen() have been removed since it now belongs as a property of each individual tip. Additionally, closeOthers(openGroup) was replaced by the new function closeAllTips().

Answer 3

Answer №2

If you're working with Angular 2, the traditional show and hide methods are not recommended or readily available. Instead, consider using ngIf to achieve a similar outcome!

(1) Start by assigning an index

<li *ngFor="let item of items; let i=index">

(2) Update the click event to include passing the index

(click)="displayItem(i)"

(3) Replace hidden attribute with ngIf

<p class="item-list__content" *ngIf="showItems[i]">

(4) Initialize an array matching the length of the items array

showItems = [false, false, false, false, false....];

(5) Modify your component's display function as follows

displayItem(index){
    for(i=0; i < this.items.length; i++){
       this.showItems[i] = false; 
    } 
    this.showItems[index] = true;
}

Answer 4

If you're working with Angular 2, the traditional show and hide methods are not recommended or readily available. Instead, consider using ngIf to achieve a similar outcome!

(1) Start by assigning an index

<li *ngFor="let item of items; let i=index">

(2) Update the click event to include passing the index

(click)="displayItem(i)"

(3) Replace hidden attribute with ngIf

<p class="item-list__content" *ngIf="showItems[i]">

(4) Initialize an array matching the length of the items array

showItems = [false, false, false, false, false....];

(5) Modify your component's display function as follows

displayItem(index){
    for(i=0; i < this.items.length; i++){
       this.showItems[i] = false; 
    } 
    this.showItems[index] = true;
}

Answer 5

Answer №3

this represents the instance of the current class itself. This means:

const instance = new SabiasQueComponent()

When you use this within the class, you are accessing the properties of that specific instance. For example (the code is not valid, but for demonstration purposes):

this.tips === instance.tips
this._isOpen === instance._isOpen

Whenever the showContent method is called, the value of _isOpen is set on the instance, making all panels open simultaneously. Ideally, you should have an isOpen property for each panel to manage their individual states. The closing logic in the closeOthers function is correct, but it's the opening logic that needs adjustment.

There are 3 key points to focus on: 1. Remove the _isOpen property from the instance. 2. Open the clicked panel instead of modifying the instance's property. 3. Update references to the appropriate values in the template.

To address the first two points:

export class SabiasQueComponent implements OnInit {
     // Removed _isOpen.

     // Store the open state in panels
     private tips : Array<any> = [
         {
             heading: 'Title 1',
             content: 'content',
             isOpen: false // Individual state.
         },
         // Additional panels...
     ]

     toggleContent(index: number) {
          this.tips[index].isOpen = !this.tips[index].isOpen
          this.closeOthersExcept(index)
     }

     closeOthersExcept(index: number) {
         this.tips.forEach((tip, tipIndex) => {
             if (index !== tipIndex) {
                 tip.isOpen = false
             }
         })
     }

     // No other methods or setters required.
}

Now, in your template, refer to the specific tip's isOpen value and pass the index when calling the opening method:

<ul class="tips-list">
  <li *ngFor="let tip of tips; let index = index">
    <h3 class="tips-list__title" 
        [ngClass]="{'tips-list__title--active' : tip.isOpen}" (click)="showContent(index)">
        {{ tip.heading }}    
    </h3>
    <p class="tips-list__answer" [hidden]="!tip.isOpen">
      {{ tip.content }}  
    </p>
  </li>
</ul>

With these adjustments, your functionality should now align with your initial intentions.

Answer 6

this represents the instance of the current class itself. This means:

const instance = new SabiasQueComponent()

When you use this within the class, you are accessing the properties of that specific instance. For example (the code is not valid, but for demonstration purposes):

this.tips === instance.tips
this._isOpen === instance._isOpen

Whenever the showContent method is called, the value of _isOpen is set on the instance, making all panels open simultaneously. Ideally, you should have an isOpen property for each panel to manage their individual states. The closing logic in the closeOthers function is correct, but it's the opening logic that needs adjustment.

There are 3 key points to focus on: 1. Remove the _isOpen property from the instance. 2. Open the clicked panel instead of modifying the instance's property. 3. Update references to the appropriate values in the template.

To address the first two points:

export class SabiasQueComponent implements OnInit {
     // Removed _isOpen.

     // Store the open state in panels
     private tips : Array<any> = [
         {
             heading: 'Title 1',
             content: 'content',
             isOpen: false // Individual state.
         },
         // Additional panels...
     ]

     toggleContent(index: number) {
          this.tips[index].isOpen = !this.tips[index].isOpen
          this.closeOthersExcept(index)
     }

     closeOthersExcept(index: number) {
         this.tips.forEach((tip, tipIndex) => {
             if (index !== tipIndex) {
                 tip.isOpen = false
             }
         })
     }

     // No other methods or setters required.
}

Now, in your template, refer to the specific tip's isOpen value and pass the index when calling the opening method:

<ul class="tips-list">
  <li *ngFor="let tip of tips; let index = index">
    <h3 class="tips-list__title" 
        [ngClass]="{'tips-list__title--active' : tip.isOpen}" (click)="showContent(index)">
        {{ tip.heading }}    
    </h3>
    <p class="tips-list__answer" [hidden]="!tip.isOpen">
      {{ tip.content }}  
    </p>
  </li>
</ul>

With these adjustments, your functionality should now align with your initial intentions.

Display one element in Angular 2 while concealing the rest

Answer №1

Answer №2

Answer №3

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