Microsoft JScript运行时错误：无法获取属性'removeChild'的值：对象为null或未定义

Question

I'm working on an asp.net mvc 3 application. The title tells what problem I have. I will describe how I get this error.

I'm using JavaScript to upload image from my razor view. The script is not that long so I'll post it here :

function fileUpload(form, action_url, div_id) {
        // Create the iframe...
        var iframe = document.createElement("iframe");
        iframe.setAttribute("id", "upload_iframe");
        iframe.setAttribute("name", "upload_iframe");
        iframe.setAttribute("width", "0");
        iframe.setAttribute("height", "0");
        iframe.setAttribute("border", "0");
        iframe.setAttribute("style", "width: 0; height: 0; border: none;");

        // Add to document...
        form.parentNode.appendChild(iframe);
        window.frames['upload_iframe'].name = "upload_iframe";

        iframeId = document.getElementById("upload_iframe");

        // Add event...
        var eventHandler = function () {

            if (iframeId.detachEvent) iframeId.detachEvent("onload", eventHandler);
            else iframeId.removeEventListener("load", eventHandler, false);

            // Message from server...
            if (iframeId.contentDocument) {
                content = iframeId.contentDocument.body.innerHTML;
            } else if (iframeId.contentWindow) {
                content = iframeId.contentWindow.document.body.innerHTML;
            } else if (iframeId.document) {
                content = iframeId.document.body.innerHTML;
            }

            document.getElementById(div_id).innerHTML = content;

            // Del the iframe...
            setTimeout('iframeId.parentNode.removeChild(iframeId)', 250);
        }

        if (iframeId.addEventListener) iframeId.addEventListener("load", eventHandler, true);
        if (iframeId.attachEvent) iframeId.attachEvent("onload", eventHandler);

        // Set properties of form...
        form.setAttribute("target", "upload_iframe");
        form.setAttribute("action", action_url);
        form.setAttribute("method", "post");
        form.setAttribute("enctype", "multipart/form-data");
        form.setAttribute("encoding", "multipart/form-data");

        // Submit the form...
        form.submit();

        document.getElementById(div_id).innerHTML = "Uploading...";
        form.setAttribute("action", '/forms/displayform');
    }

By using this script I get the image in my controller where I do my business logic so I'm not sure if it's really the script that is causing this, but I can't find another reason while debugging. So when the controller finish its work I get a new tab open in the visual studio 2010 titled Script block[dynamic] and the following code is there :

function anonymous()
{
iframeId.parentNode.removeChild(iframeId)
}

which is actually part of my JavaScript :

    // Del the iframe...
    setTimeout('iframeId.parentNode.removeChild(iframeId)', 250);

I have very basic knowledge about JS. I use this code but I don't understand some parts of it. Here - by the comment and the code itself is somewhat obvious what's going on but if I comment this and try to upload an image I don't get error and this is something very tempting to do, but I think that most probably the code is OK and the reason to get this error is somewhere else, so I post here to get any help on what may cause this error and how can it be fixed?

PS

And this is the form that I use for uploading the image:

@using (Html.BeginForm("Upload", "Forms", FormMethod.Post))
{
    <input name=@Model[0].DocumentId type="hidden" />

    <input type="file" name="datafile" id="file" onchange="readURL(this);" />
    <input type="button" name="Button" value="Upload Image" id="UploadButton" onclick="fileUpload(this.form,'/forms/upload','uploadImg'); return false;"/>
    <div id="uploadImg" style="display: inline-block;">
        <img id="blah" src="#" alt="your image" style="display:none;"/>
    </div>
}

Answer 1

This is the syntax for setTimeout

setTimeout(function(),milliseconds);

So , you should do something like this

setTimeout(function(){
           iframeId.parentNode.removeChild(iframeId);
           }, 250);