input file 选择文件后自动执行上传

$('body').on('change','#upLoad',function(){
    var formData = new FormData();
    var name = $($(this)).val();
    var files = $($(this))[0].files[0];
    formData.append("file", files);
    formData.append("name", name);
    //另外加的参数
    formData.append("act", "PostImg"); 
    var index = layer.msg('正在提交中....');
    $.ajax({
        url: 'img.php',
        type: 'POST',
        data: formData,
        processData: false,
        contentType: false, 
        dataType: 'json',
        success:function (res) {
            alert('上传成功');
        }
        ,error:function (res) {
            alert('错误');
        }
    });
})