js导出二进制文件流

map = {
    
    
                                searchType: searchType,
                                searchName: searchName,
                                createTime: createTime,
                                category: category,
                                customerStatus: where.customerStatus
                            }
                            url = layui.setter.base_server + "api/cybank/customer/exportList";   //请求的URl
                            xhr = new XMLHttpRequest();		//定义http请求对象
                            xhr.open("POST", url, true);
                            xhr.setRequestHeader("Content-type", "application/json;charset=utf-8");
                            xhr.setRequestHeader("authorization", layui.user.getAccessToken());
                            xhr.setRequestHeader("client-key", layui.user.initClientKey());
                            xhr.send(JSON.stringify(map));
                            xhr.responseType = "blob";  // 返回类型blob
                            xhr.onload = function () {
    
       // 定义请求完成的处理函数，请求前也可以增加加载框/禁用下载按钮逻辑
                                if (this.status === 200) {
    
    
                                    var blob = this.response;
                                    var reader = new FileReader();
                                    reader.readAsDataURL(blob);  // 转换为base64，可以直接放入a表情href
                                    reader.onload = function (e) {
    
    
                                        // console.log(e);			//查看有没有接收到数据流
                                        // 转换完成，创建一个a标签用于下载
                                        var a = document.createElement('a');
                                        a.download = "客户信息导出" + Date.parse(new Date()) + ".xlsx";			//自定义下载文件名称
                                        a.href = e.target.result;
                                        $("body").append(a);    // 修复firefox中无法触发click
                                        a.click();
                                        $(a).remove();
                                        utils.successMsg("导出成功，请稍等一会");
                                    }
                                } else {
    
    
                                    alert("出现了未知的错误!");
                                }
                            }