JavaScript form Validation – textarea field to display an alert if no text has been entered

I can’t seem to target the textarea field in this function.

I’m essentially using HTML “required” validation for the first three input fields, but for the textarea, I simply want to display an alert if the textarea field is empty when the user submits the form.

Or possibly, I’d like to display text within the textarea field, stating “please enter more information”, if the user attempts to submit the form without filling that area in.

      <form action="" class="contactForm" method="POST" id="contactForm">
                        <label for="name">Name:</label>
                        <input type="text" id="name" name="name" required><br>
                        <label for="number">Number:</label>
                        <input type="number" id="number" name="number" required><br>
                        <label for="email">Email:</label>
                        <input type="email" id="email" name="email" required><br>
                        <textarea id= "textArea" rows ="3" cols ="23" name="finalMessage " form="contactForm" placeholder="Enter your fitness goals..."></textarea><br>
                        <button id="buttonID">Submit</button>
                    </form>

JavaScript

function formValidation(e) {
    e.preventDefault();
    const form = document.getElementById("contactForm");
    const textArea = document.getElementById("textArea").value;

    if(textArea.value === ""){
        alert("please enter more information");
    }

    document.getElementById("buttonID").addEventListener("click", function () {
        form.submit();
    });

} formValidation();