angularbootstrap-4scrollspy

How to use bootstrap scrollspy on angular 7 project?


I have transform basic html page with bootstrap scrollspy component and my nav doesn't work (no change when page scroll).

I have install bootstrap 4 with the command below :

npm install bootstrap

There is no change on page scroll or when i click on menu there is no "active" flag.

Can you help me ? Thanks :)


Solution

  • check the solution here using a directive for spyScroll. It listens to scroll event on the page and highlights the current section in view.

    import { Directive, Injectable, Input, EventEmitter, Output, ElementRef, HostListener } from '@angular/core';
    
    @Directive({
        selector: '[scrollSpy]'
    })
    export class ScrollSpyDirective {
        @Input() public spiedTags = [];
        @Output() public sectionChange = new EventEmitter<string>();
        private currentSection: string;
    
        constructor(private _el: ElementRef) {}
    
        @HostListener('scroll', ['$event'])
        onScroll(event: any) {
            let currentSection: string;
            const children = this._el.nativeElement.children;
            const scrollTop = event.target.scrollTop;
            const parentOffset = event.target.offsetTop;
            for (let i = 0; i < children.length; i++) {
                const element = children[i];
                if (this.spiedTags.some(spiedTag => spiedTag === element.tagName)) {
                    if ((element.offsetTop - parentOffset) <= scrollTop) {
                        currentSection = element.id;
                    }
                }
            }
            if (currentSection !== this.currentSection) {
                this.currentSection = currentSection;
                this.sectionChange.emit(this.currentSection);
            }
        }
    
    }
    

    In AppComponent:

    import { Component } from '@angular/core';
    
    @Component({
      selector: 'my-app',
      templateUrl: './app.component.html',
      styleUrls: [ './app.component.css' ]
    })
    export class AppComponent  {
      currentSection = 'section1';
    
      onSectionChange(sectionId: string) {
        this.currentSection = sectionId;
      }
    
      scrollTo(section) {
        document.querySelector('#' + section)
        .scrollIntoView();
      }
    }
    

    AppComponent.html:

     <h1>Current Section : [{{currentSection}}]</h1>
    
    
    <h2>Menu</h2>
    <div (click)="scrollTo('section1')" [ngClass]="{ 'current-section': currentSection === 'section1' }">Section 1 
    </div>
    <div (click)="scrollTo('section2')" [ngClass]="{ 'current-section': currentSection === 'section2' }">Section 2 
    </div>
    <div (click)="scrollTo('section3')" [ngClass]="{ 'current-section': currentSection === 'section3' }">Section 3
    </div>
    <div (click)="scrollTo('section4')" [ngClass]="{ 'current-section': currentSection === 'section4' }">Section 4 
    </div>
    <br/>
    
    
    <div id="parentDiv" scrollSpy [spiedTags]="['DIV']" (sectionChange)="onSectionChange($event)" style="height:150px;overflow-y: scroll;">
      <div id="section1">
        <h2 style="margin:0">Section 1</h2>
        <lorem-ipsum></lorem-ipsum>
      </div>
      <div id="section2">
        <h1>Section 2</h1>
        <lorem-ipsum></lorem-ipsum>
      </div>
      <div id="section3">
        <h1>Section 3</h1>
        <lorem-ipsum></lorem-ipsum>
      </div>
      <div id="section4">
        <h1>Section 4</h1>
        <lorem-ipsum></lorem-ipsum>
      </div>
    </div>
    <br/>
    

    In app.component.css:

    .current-section {
      background-color: cornflowerblue
    }
    .current-section::after { 
      content: "\039e";
      background-color: yellow; 
      color: red;
    
    }