load external java script file dynamically after navigation in angular2+

Example.component.ts

import { Component, OnInit } from '@angular/core';
import { LoadJsService } from './load-js.service';

@Component({
  selector: 'app-home',
  templateUrl: './example.component.html',
  styleUrls: ['./example.component.css']
})
export class HomeComponent implements OnInit {

  constructor(private jsObj: LoadJsService) {
     
   }

   ngOnInit() { 
    this.loadScripts();  
  }

  private loadScripts() {
    this.jsObj.load('customMinJs').then(data => {     
    }).catch(error => console.log(error));
  }

}

LoadJsService.ts

import { Injectable } from '@angular/core';

interface Scripts {
  name: string;
  src: string;
}

export const ScriptStore: Scripts[] = [
  {name: 'customMinJs', src: './assets/js/scripts/custom.min.js'}
];

declare var document: any;

@Injectable({
  providedIn: 'root'
})

export class LoadJsService {
  private scripts: any = {};
  
  constructor() {
    ScriptStore.forEach((script: any) => {
      this.scripts[script.name] = {
        loaded: false,
        src: script.src
      };
    });
   }

   load(...scripts: string[]) {
    const promises: any[] = [];
    scripts.forEach((script) => promises.push(this.loadScript(script)));
    return Promise.all(promises);
    }

    loadScript(name: string) {
      return new Promise((resolve, reject) => {
        if (!this.scripts[name].loaded) {
          console.log("if of first if")
          //load script
          let script = document.createElement('script');
          script.type = 'text/javascript';
          script.src = this.scripts[name].src;
          if (script.readyState) {  //IE
              console.log("second of first if")
              script.onreadystatechange = () => {
                  if (script.readyState === "loaded" || script.readyState === "complete") {
                      script.onreadystatechange = null;
                      this.scripts[name].loaded = false;
                      resolve({script: name, loaded: true, status: 'Loaded'});
                  }
              };
          } else {  //Others
              console.log("else of second if")
              script.onload = () => {
                  this.scripts[name].loaded = false;
                  resolve({script: name, loaded: true, status: 'Loaded'});
              };
          }
          script.onerror = (error: any) => resolve({script: name, loaded: false, status: 'Loaded'});
          document.getElementsByTagName('head')[0].appendChild(script);
        } else {
          console.log("else of first if")
          resolve({ script: name, loaded: true, status: 'Already Loaded' });
        }
      });
    }
   
}