Angular 6 - Adding script at component level and checking if it exists

Question

I have a script that I would like to run on one component only. I have managed to achieve adding the script on the component but a couple of things happen that I'm not entirely sure how to resolve.

1. If I navigate to the component, the script is added to the DOM, but it isn't firing. If I refresh the page, it works
2. If I navigate away to another component and return, the script is added again, and it can keep building up

component.ts

import { Component, OnInit } from '@angular/core';
import { Renderer2, Inject } from '@angular/core';
import { DOCUMENT } from '@angular/platform-browser';

@Component({
  selector: 'app-privacy',
  templateUrl: './privacy.component.html',
  styles: []
})
export class PrivacyComponent implements OnInit {

  constructor(private _renderer2: Renderer2, @Inject(DOCUMENT) private _document) {
    let s = this._renderer2.createElement('script');
    s.type = `text/javascript`;
    s.src = `../../assets/scripts/privacy.js`;

    this._renderer2.appendChild(this._document.body, s);
   }

  ngOnInit() {
  }

}

Answer 1

You need to add the onload (if you need to support IE make sure to also support onreadystatechange) handler to your script element which can call a function you want to execute when the script is finished loading.

To remove the script onNgDestroy, save a reference of createElement? on the Component and remove this in Destroy lifecycle hook.

import { Component, OnInit, OnDestroy } from '@angular/core';
import { Renderer2, Inject } from '@angular/core';
import { DOCUMENT } from '@angular/platform-browser';

@Component({
  selector: 'app-privacy',
  templateUrl: './privacy.component.html',
  styles: []
})
export class PrivacyComponent implements OnInit, OnDestroy {
  private s: any;
  constructor(private _renderer2: Renderer2, @Inject(DOCUMENT) private _document) {
    this.s = this._renderer2.createElement('script');
    this.s.type = `text/javascript`;
    this.s.src = `../../assets/scripts/privacy.js`;
    this.s.onload = this.doneLoading;

    this._renderer2.appendChild(this._document.body, this.s);
  }

  doneLoading () {
    // do what you need to do
  }


  ngOnDestroy() {
    // this removes the script so it won't be added again when the component gets initialized again.
    this._renderer2.removeChild(this._document.body, this.s)
  }

  ngOnInit() {
  }

}