msal-login.js

return new Promise((resolve) => {
  let scopes = {
    // To acquire Sharepoint token
    scopes: ['https://{{tenant ID}}.sharepoint.com/.default', 'openid', 'profile'],
    // To acquire Graph API token
    scopes: ['.default', 'openid', 'profile'],
    loginHint: null
  };
  context.handleRedirectCallback((error, response) => {
    if (error) {
      // TODO: e.g. track into analytics
    } else if (window.parent === window) {
      if (response.tokenType === 'access_token' && response.accessToken) {
        resolve(response.accessToken);
      }
    }
  });

  if (!context.isCallback(window.location.hash)) {
    if (context.getAccount()) {
      context.acquireTokenSilent(scopes).then((response) => {
        if (response.accessToken) {
          resolve(response.accessToken);
        }
      }).catch((_error) => {
        context.acquireTokenRedirect(scopes);
      });
    } else {
      context.loginRedirect(scopes);
    }
  }
});