Javascript variable not displayed in HTML file

Question

Whats wrong with my code . The title is not displayed within the div banAdT :

<form action="" method="post" enctype="multipart/form-data">
    <p>
        Banner Ad Name :<br />
        <input type="text" name="bannerAdName" id="bannerAdName" />
    </p>
    <p>
        Your web page :<br />
        <input type="text" name="bannerAdWeb" id="bannerAdWeb" />
    </p>
    <p>
        Ad image :<br />
        <input type="file" name="bannerAdImage" id="bannerAdImage"/>
    </p>
    <p>
        Title :<br />
        <input type="text" name="bannerAdTitle" id="bannerAdTitle" />
    </p>
    <p>
        Description :<br />
        <textarea name="bannerAdDesc" id="bannerAdDesc" ></textarea>
    </p>
    <div id="button"><input type="button" value="VIEW" onclick="return upload()"/></div>

    <input type="hidden" value="POST" />
</form>
<div id="popupContact">
        <a id="popupContactClose">x</a>
        <div id="contactArea">
            <div id="banAdT">
                <script>document.write(document.getElementById("bannerAdTitle").value);</script> <!-- Displays nothing -->
            </div>
            <img src="" id="preview" width="120" height="120" />
        </div>
    </div>

Answer 1

That's because when the script runs, the element bannerAdTitle won't have a value. I'm not exactly sure what you're trying to do, but you probably want to attach a change event listener to the bannerAdTitle input, and write the value from there:

document.getElementById("bannerAdTitle").onchange = function() {
    document.getElementById("banAdT").innerHTML = this.value;
}

That will write the value of bannerAdTitle in the banAdT element every time the change event is fired.

Answer 2

document.write is executed as the page loads, but at that point you haven't given bannerAdTitle a value - the INPUT is empty.