Javascript childelementcount无法在IE 8及更低版本中运行（在其他浏览器中很好）

我有一个javascript函数来添加动态文本框，我使用childelementcount来计算添加的智能节点。它适用于IE 8及更低版本以外的所有浏览器。所以我尝试了childNodes.length，它在每个浏览器中给出了不同的限制。我该如何解决这个问题？真的有点帮助家伙。下面是函数。

Hi,
I have a javascript function to add dynamic textboxes and I was using childelementcount to count the chile nodes added. It works fine in every browser other than IE 8 and lower. So I tried childNodes.length which gives me different limit in each browser. How do I solve this? Really appreacite some help guys. Below is the function.

function AddTextBox() {
        if (document.getElementById("TextBoxContainer").childNodes.length < 21) {
            var div = document.createElement('DIV');
            div.innerHTML = GetDynamicTextBox("");
            document.getElementById("TextBoxContainer").appendChild(div);
        }
    }