fb-signin-button.js

function loginFb() {
  if (!window.FB) return;

  let fbToken = null;

  function loginMethod(response) {
    if (response.authResponse) {
      if (response.authResponse.accessToken) {
        fbToken = response.authResponse.accessToken;
        const res = await $axios.$get(`https://graph.facebook.com/${response.authResponse.userID}?fields=id,first_name,last_name,email,picture,location&access_token=${fbToken}`);
      }
    } else {
      console.log("User cancelled login or did not fully authorize.");
    }
  }

  window.FB.login(loginMethod);
}

init-sdk.js

const FB_APP_ID = ;

window.fbAsyncInit = function() {
  window.FB.init({
    appId: FB_APP_ID,
    autoLogAppEvents: true,
    xfbml: true,
    version: "v12.0"
  });

  (function (d, s, id) {
    var js,
      fjs = d.getElementsByTagName(s)[0];
    if (d.getElementById(id)) {
      return;
    }
    js = d.createElement(s);
    js.id = id;
    js.src = "https://connect.facebook.net/en_US/sdk.js";
    fjs.parentNode.insertBefore(js, fjs);
  })(document, "script", "facebook-jssdk");
};
//<script async defer crossorigin="anonymous" src="https://connect.facebook.net/en_US/sdk.js"></script>