<input type="file" id ="file" />
<script>
// 普通上传文件
$("#file").bind("change",function(){
    //获取文件
    var fileObj = document.getElementById("file").files[0];
    var form = new FormData();
    form.append("user_avatar", fileObj);                           // 文件对象
    var xhr = new XMLHttpRequest();
    xhr.open("post",api_url + 'user/avatar', true);
    xhr.send(form);
    xhr.onreadystatechange = function (){
        if(xhr.readyState ==  4 && xhr.status == 200){
                console.log(xhr.responseText);
                var res = eval(xhr.responseText);
                console.log(res);
                $avatar = $("<li />",{class:"weui_uploader_file",style:"background-image:url(/"+res[0]+")"});
                console.log($avatar);
                $weui_uploader_files.append($avatar);
        }
    }
});
</script>