Contact info member registration checkbox

Hello, I am using the following code to register new members on a site using a custom form. My problem is I cannot figure out how to get the terms and conditions checkbox to work with it. When I put .value after it gives an error message but still creates a new user. If I put .checked it gives the success message but won’t actually register the user. Thanks for the help.

import wixUsers from 'wix-users';
import wixLocation from 'wix-location';

$w.onReady(function () {

  $w('#submit').onClick( () => {
 let emails = [];
 let labels = [];  
 
    emails.push($w('#email').value);
 // register as member using form data
    wixUsers.register($w('#email').value, $w('#password').value, {
 "contactInfo": {
 "firstName": $w('#firstName').value,
 "lastName": $w('#lastName').value,
 "emails": emails,
 "labels": labels,
 "additionalMembers": $w('#textBox1').value, 
 "termsConditions": $w('#TC').WHAT GOES HERE?,
        }     
      })
  });
  });