图片上传与后台交互

HTML:

<div class="row">
      <div class="qsc_img col-md-4">
           <p class="qsc_img_del" style="display: none;"><i class="fa fa-close" onclick="del_img(this)"></i> </p>
      </div>
      <input type='file' onchange='previewImage(this)' style='display: none;' class='previewImg'>
　　　<input type='hidde' value='id'>

      <div class='preview col-md-8'>
         <a class="btn qsc_img_btn" onclick="img_self(this)">上传</a>
         <a class="qsc_img_example" data-example="qsc_example_business" href="javascript:;" title="示例">示例</a>
      </div>
</div>

JS

function previewImage(file)
{
    var self = $(file);
    var div = self.prev(".qsc_img");
    var leg = div.find("img").length;
　　var formId = $('input["name=id"]') 
    if(leg==1) {
        return;
    }
    if (file.files && file.files[0])
    {
        var reader = new FileReader();
        reader.readAsDataURL(file.files[0]);
        reader.onload = function(evt){
            $('<img src="' + this.result +'" class="imghead qsc_img_circle">').appendTo(div);
        };
        var img = self.prev(".qsc_img").find('imghead');
      //调用ajax;upload(formId);
    }
}

//自动触发input类型为file的click事件
function img_self(thiz) {
    var self = $(thiz);
    self.parents(".preview").prev(".previewImg").trigger("click");
}

AJAX

function upload(id){
    var form = new FormData(document.getElementById(id));
    $.ajax({
        url:"url",
        type:"post",
        data:form,
        processData:false,
        contentType:false,
        dataType:"json",
        success:function(data){
            if(data.msg==200){
                swal({
                    title: "",
                    html: false,
                    text: "上传菜单图片成功",
                    type: "success",
                    showCancelButton: false,
                    confirmButtonText: "确定",
                    closeOnConfirm: true
                };
            }else{
                swal({
                    title: "",
                    html: false,
                    text: "上传菜单图片失败",
                    type: "error",
                    showCancelButton: false,
                    confirmButtonText: "确定",
                    closeOnConfirm: true
                });

            }
        },
        error:function(e){
            alert("错误！！");
        }
    });
}