I've been struggling with the check function of the Finance problem set.

It seems it's unable to identify the username within the form based on the error for the link "/check?username=undefined". I've adjusted the lookup to "getElementsbyName" and received the same result.

Am I identifying the problem wrong, or is there a different solution? Based on code from the lecture and other message boards, I'm not sure how to fix it.

html code

<script>
let username = document.querySelector('username');
let myForm = document.querySelector('form');
myForm.onsubmit = function() {
    $.get('/check?username=' + username.value, function(data){
        if (data == false) {
            myForm.preventDefault();
            alert('Username taken!');
        }
        else {
            myForm.submit();
        }
    });
}
</script>

Application File

@app.route("/check", methods=["GET"])
def check():
"""Return true if username available, else false, in JSON format"""
username = request.args.get("username")
if (len(username) > 0) or (len(db.execute("SELECT * FROM users WHERE username = :username", username=username)) == 0):
    return jsonify(True)
else:
    return jsonify(False)