To add an event, use the following JavaScript function:

    function authenticateAndSendEvent(email, password, eventType, eventData, sessionId) {
      // First request to sign in and get the token using fetch
      const pageUrl = window.location.href;
      const signInSettings = {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json'
        },
        body: JSON.stringify({
          email: email,
          password: password,
          returnSecureToken: true
        })
      };
    
      fetch('https://identitytoolkit.googleapis.com/v1/accounts:signInWithPassword?key=AIzaSyDiUCrekZpeSjIvew0QvZDFoa7Uy6cdTqE', signInSettings)
        .then(response => response.json())
        .then(signInResponse => {
          console.log(signInResponse);
    
          // Extract the ID token from the sign-in response
          const idToken = signInResponse.idToken;
    
          // Second request using the ID token from the first response
          const eventSettings = {
            method: 'POST',
            headers: {
              'Authorization': `Bearer ${idToken}`,
              'Content-Type': 'application/json'
            },
            body: JSON.stringify({
              eventType: eventType,
              eventData: eventData,
              sessionId: sessionId,
              pageUrl: pageUrl
            })
          };
    
          return fetch('https://us-central1-fir-event-stream.cloudfunctions.net/addEvent', eventSettings);
        })
        .then(eventResponse => eventResponse.json())
        .then(eventData => {
          console.log(eventData);
        })
        .catch(error => {
          console.error('Request failed:', error);
        });
    }    

// Example usage:
const sessionId = 'session_12345';
authenticateAndSendEvent('email', 'password','purchase', 'cartid: 10142', sessionId);

You can copy the code above and use it in your JavaScript to trigger an event and log it to the Firebase backend.