IO is not defined [duplicate] – Blancer.com Tutorials and projects

I’m working on a web app that uses socket.io for client to server communication.
When I run the site, in the inspect tab it gives me Uncaught ReferenceError: io is not defined at script.js:1 (anonymous) @ script.js:1
Here is my HTML:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Hack.top - Sign Up</title>
    <link href="../style.css" rel="stylesheet" type="text/css">
  </head>
    

    <body>

        <nav>
            <a href="/" class="first">
                <div class='title-container'><h3>Hack.top</h3><h3 id='title-underscore'>&#95;</h3></div>
            </a>

            <div class="links">
                <a href="">learn more</a>

                <a href="">competitions</a>

                <a href="">contact</a>

                <!-- <a href="/signup">
                    <button>sign up</button>
                </a> -->
            </div>
        </nav>

        <main>
            <div class="info signup">
                <h3>Hello!</h3>
                
                <p>Sign up to start hacking.</p>

        <input type="email" placeholder="[email protected]" id="email">

                <input type="text" placeholder="Username" id="username">

                <input type="password" placeholder="Password" id="password">
                
                <input type="password" placeholder="Confirm password" id="confirmPassword">

                <p>Already have an account? <a href="/login">log in</a></p>

                <button id="signUpButton">sign up</button>
            </div>
        </main>


        <script src="../script.js"></script>
    <script src="/socket.io/socket.io.js"></script>
  </body>
</html>

And my client-side JS:

socket = io();

socket.on('logged', function (res){
  if(res.err){
    //res.message...
  } else {
  
  }
});

document.getElementById("signUpButton").addEventListener("click", createAccount);

function login(){
  const username = document.getElementById('username').value;
  const password = document.getElementById('password').value;

  const user = {
    'username': username,
    'password': password
  }
  
  socket.emit('login', user);
}


function createAccount(){
  const email = document.getElementById('email').value;
  const username = document.getElementById('username').value;
  const password = document.getElementById('password').value;
  const confirmPassword = document.getElementById('confirmPassword').value;

  if(password != confirmPassword){
    //alert user
  }

  const user = {
    'username': username,
    'password': password,
    'email': email
  }

  socket.emit('createAccount', user);
}

I don’t think server side JS is necessary for this issue but if someone needs to see just ask and I’ll add it.
Not sure why this is happening, thanks.