Why won't JS redirect the webpage when statement is true?

I have an input for username and one for password. When the username and/or password don't match, I successfully get the "alert", but when they do match, nothing happens. I can't figure out what I'm doing wrong.

I have tried windows.location.replace as well, with the same results.

function user1() {
    var user = document.getElementById('username').value
    var pass = document.getElementById('password').value
  
    if (user == "admin" && pass == "password1") {
        window.location ("http://stackoverflow.com");
    }
    else {
        alert('incorrect username or password')
    }
}

<form>
    <label for="username" id="user">User</label>
    <input type="text" placeholder="Username" name="username" id="username">
    <br>
    <label for="password">Pass</label>
    <input type="password" name="password" id="password" placeholder="Password">
    <br>
    <button onclick="user1()">Submit</button>
</form>