前台图片上传展示JS（单张图片展示）

<script type="text/javascript">
    //下面用于多图片上传预览功能
    function setImagePreviews(avalue) {
        var docObj = document.getElementById("doc");
        var dd = document.getElementById("dd");
        dd.innerHTML = "";
        var fileList = docObj.files;
        for (var i = 0; i < fileList.length; i++) {
            dd.innerHTML += "<div style='float:left' ><img id='img" + i + "'  /> </div>";
            var imgObjPreview = document.getElementById("img"+i);
            if (docObj.files && docObj.files[i]) {
                //火狐下，直接设img属性
                imgObjPreview.style.display = 'block';
                imgObjPreview.style.width = '200px';
                imgObjPreview.style.height = 'auto';
                //imgObjPreview.src = docObj.files[0].getAsDataURL();
                //火狐7以上版本不能用上面的getAsDataURL()方式获取，需要一下方式
                imgObjPreview.src = window.URL.createObjectURL(docObj.files[i]);
            }
            else {
                //IE下，使用滤镜
                docObj.select();
                var imgSrc = document.selection.createRange().text;
                alert(imgSrc)
                var localImagId = document.getElementById("img" + i);
                //必须设置初始大小
                localImagId.style.width = "200px";
                localImagId.style.height = "auto";
                //图片异常的捕捉，防止用户修改后缀来伪造图片
                try {
                    localImagId.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";
                    localImagId.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgSrc;
                }
                catch (e) {
                    alert("您上传的图片格式不正确，请重新选择!");
                    return false;
                }
                imgObjPreview.style.display = 'none';
                document.selection.empty();
            }
        }  
        return true;
    }
</script>

<div style="margin :0px auto; 990px;">
<input type="file"  name="file" id="doc" multiple="multiple"  style="150px;" onChange="javascript:setImagePreviews();" accept="image/*" />
<div id="dd" style=" 990px;"></div>
</div>