SOURCE

 //获取文件
        var input = document.getElementById('add_file');
        //文件域选择文件时, 执行readFile函数
        input.addEventListener('change',readFile,false);
        function bytesToSize(bytes) {
            if (bytes === 0) return '0 B';
            var k = 1000, // or 1024
                sizes = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'],
                i = Math.floor(Math.log(bytes) / Math.log(k));
            return (bytes / Math.pow(k, i)).toPrecision(3) + ' ' + sizes[i];
        }
        function readFile(){
            var file = this.files[0];
            if(file == undefined){
                canLoad = false;
                return;
            }
            canLoad = true;
            kamName = file.name;
        }
        // 上传按钮
        $('.send_btn button ').click(function(){
            if($("#add_file").val() == ""){
                $('body').toast({
                    content:"文件不能为空",
                    duration:2000,
                    isCenter:false,
                    background:'rgba(230,0,0,0.5)',
                    animateIn:'bounceIn-hastrans',
                    animateOut:'bounceOut-hastrans',
                });
                return false;
            }else{
                if (canLoad) {
                    var file=new FormData($('#defaultForm')[0]);
                    $.ajax({
                        url: window.zd_conf.base_url+ 'upload-file/upload', //地址
                        type: 'POST',
                        dataType:'json',
                        cache: false,
                        data: [{file},{free_service:arr}],
                        processData: false,
                        contentType: false,
                        success:function(res) {
                            $('body').toast({
                                content:res.msg,
                                duration:2000,
                                isCenter:false,
                                background:'#4EA44E',
                                animateIn:'bounceIn-hastrans',
                                animateOut:'bounceOut-hastrans',
                            });
                        },
                        error:function(){
                            $('body').toast({
                                content:"数据访问错误",
                                duration:2000,
                                isCenter:false,
                                background:'rgba(230,0,0,0.5)',
                                animateIn:'bounceIn-hastrans',
                                animateOut:'bounceOut-hastrans',
                            });
                        }
                    })
                }
            }
        })

	  <form method="post" id="defaultForm" enctype="multipart/form-data">
        <div class="send_title">
            <label>
                <input style="position:absolute;opacity:0;" type="file" name="file" id="add_file" accept="image/gif,image/jpeg,image/x-png"/>
                <img style="width: 40px;height: 40px;margin-top:20px;"  src="img/send.png">
                <span style="margin-top:28px;margin-left:16px;position: absolute;">上传列表</span>
            </label>
        </div>
        </form>

button{
	border:1px solid #ccc;
	cursor:pointer;
  display:block;
  margin:auto;
  position:relative;
  top:100px;
}