判断上传文件类型，上传图片

        //加载图片检查
        function loadImage(img) {
            var filePath = img.value;
            var fileExt = filePath.substring(filePath.lastIndexOf("."))
                .toLowerCase();
            if (!checkFileExt(fileExt)) {
                parent.layer.msg('您上传的文件不是图片,请重新上传！', { icon: 5 });  
                img.value = "";
                return false;
            }
            if (img.files && img.files[0]) {

                //parent.layer.msg('你选择的文件大小'+(img.files[0].size / 1024/1024).toFixed(2)+"M", { icon: 1 });  
                if((img.files[0].size / 1024/1024).toFixed(2)>5){

                    parent.layer.msg('您选择的文件太大（'+(img.files[0].size / 1024/1024).toFixed(2)+"M）", { icon: 5 });  
                    return false;
                }
            } else {
                img.select();
                var url = document.selection.createRange().text;
                try {
                    var fso = new ActiveXObject("Scripting.FileSystemObject");
                } catch (e) {
                    parent.layer.msg('如果您用的是ie8以下 请将安全级别调低！', { icon: 5 });  
                }
                parent.layer.msg("文件大小为：" + (fso.GetFile(url).size / 1024).toFixed(0) + "kb", { icon: 5 });  
                return false;
            }
            return true;
        }
        //后缀
        function checkFileExt(ext) {
            if (!ext.match(/.jpg|.gif|.png|.bmp/i)) {
                return false;
            }
            return true;
        }