js实现图片上传前的预览,实现完美兼容Firefox3,IE6,IE7,IE8和IE9的显示问题

<script type="text/javascript" language="javascript">
function PreviewImg(imgFile){
     document.getElementById("idImg").style.display = "none";//隐藏初始化图片的显示,让过滤器显示
     var newPreview=document.getElementById("newPreview");
     remove(newPreview);
     
     var imgDiv=document.createElement("div");
     document.body.appendChild(imgDiv);
     imgDiv.style.filter="progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";
     imgDiv.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src=imgFile.target.value;
        var img_object = document.getElementById("engineroom_layout_addr");
        img_object.style.display = "inline";
        img_object.src = addrObject.value;
        if (!img_object.width || img_object.width > 300) {
            imgDiv.style.width = "300px";
        }
        if (!img_object.height || img_object.height > 200) {
            imgDiv.style.height = "200px";
        }
        addrObject.style.display = "none";
     //imgDiv.style.width="320px";
     //imgDiv.style.height="127px";
     newPreview.appendChild(imgDiv);
     
}
//使用removeChild从文档中删除DOM节点
function remove(obj) {
    var test = obj;
    var children = test.childNodes;
    for (i = 0; i < children.length; i++) {
        test.removeChild(children[i]);
    }
}
</script>

2、在页面中添加DIV层来展示，IE9默认不显示预览，可参考title的说明设置

 

<div style="padding:5px;margin-left: -5px">
        <table border="0" style="width:94%;border-collapse:collapse;background:#fff;"  title="无显示帮助：第一步：工具-- Internet选项-- 安全-- 自定义级别;第二步：向下拖，一直看到“将文件上载到服务器时包含本地目录路径”;第三步：选择启用。">
            <tr>
                <th style="background-color:#f0f0f0; height:20px;padding:5px;border:1px solid #ccc;font-weight: bolder;text-align: center;" width="40%">选择图片</th>
                <th style="background-color:#f0f0f0; height:20px;padding:5px;border:1px solid #ccc;font-weight: bolder;text-align: center;" width="70%">预览图</th>
            </tr>
            <tr>
                <td style="padding:5px;border:1px solid #ccc;"><INPUT id=engineroom_layout_addr class=inputbox name=engineroom_layout_addr/></td>
                <td align="center" style="padding:5px;border:1px solid #ccc;"><img id="idImg" style="display:none"/><div id="newPreview"></div></td>
            </tr>
        </table>
        <script type="text/javascript">
            var addrObject = document.getElementById("engineroom_layout_addr");
            addrObject.style.display = "none";//把机房显示输入框隐藏
            Ext.get('file_engineroom_layout_addr').on('change',function(obj){
                //crmsUtil.previewImg(obj.target,"idImg",300,200);//只适用于IE6
                PreviewImg(obj);
            });
            if(addrObject.value != ''){
                var img_object = document.getElementById("idImg");
                img_object.style.display = "inline";
                img_object.src = addrObject.value;
                if (!img_object.width || img_object.width > 300) {
                    img_object.width = 300;
                }
                if (!img_object.height || img_object.height > 200) {
                    img_object.height = 200;
                }
            }
        </script>
        </div>