getAccessToken.ts

import { InteractionRequiredAuthError, IPublicClientApplication } from "@azure/msal-browser";

let msalInstance: IPublicClientApplication;

export const setMsalInstance = async (instance: IPublicClientApplication) => {
  msalInstance = instance;
  await msalInstance.initialize();
}

const getAccessToken = async (scopes: string[]): Promise<string | null> => {
  let authResult = null;

  const account = msalInstance.getActiveAccount() ?? msalInstance.getAllAccounts()[0];

  try {
    authResult = await msalInstance.acquireTokenSilent({ scopes: scopes, account: account })
  }
  catch (error) {
    if (error instanceof InteractionRequiredAuthError) {
      authResult = await msalInstance.acquireTokenPopup({ scopes: scopes })
    }
  }

  return authResult ? authResult.accessToken : null;
}