I am working with multilingual project with angular and the logic for changing the language and the stylesheets is typed in the app default component, I created navbar component but I can't use the changeLanguage function because it's in the app component so I must duplicate the function and the logic in every component I make, how to solve this or how to make the functions in the app component useable in the other components?

the app components code

import { Component } from '@angular/core';
import { TranslateService } from "@ngx-translate/core";
import { Inject } from '@angular/core';
import { DOCUMENT } from '@angular/common';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss']
})
export class AppComponent {
  title = 'labsystem';

  constructor(private translateService: TranslateService, @Inject(DOCUMENT) private document: 
Document) { }

  changeLanguage(lang: string) {
    let htmlTag = this.document.getElementsByTagName('html')[0] as HTMLHtmlElement;

    htmlTag.dir = lang === "ar" ? "rtl" : "ltr";
    this.translateService.setDefaultLang(lang);
    this.translateService.use(lang);
    this.changeCssFile(lang);
  }

  changeCssFile(lang: string) {
    let headTag = this.document.getElementsByTagName("head")[0] as HTMLHeadElement;

    let existingLink = this.document.getElementById("langCss") as HTMLLinkElement;

    let bundleName = lang === "ar" ? "arabicStyle.scss" : "englishStyle.scss";

    if (existingLink) {
      existingLink.href = bundleName;
    } else {
      let newLink = this.document.createElement('link');
      newLink.rel = "stylesheet";
      newLink.id = "langCss";
      newLink.href = bundleName;
      headTag.appendChild(newLink);
    }
  }
}

I need to use these functions in the other components

CodePudding user response：

you can create a constant file like app.constant.ts and there you can do

export myFunction = () => {
  // your code here
}

and, simply call that function by reference everywhere.

import {myFunction} from './app.constant'