生成csv下载--数据量大的时候

 exp2() {
        let that = this;

        const tHeader = ["卡名称", "卡号", "卡类型", "Id", "手机号", "用户姓名", "余额", "开卡时间"]; //表头
        const filterVal = ["CardName", "CardNo", "CardType", "Id", "Phone", "RealName", "Balance", "UploadTime"]; //对应的值
        const list = that.dc; //要导出的数据

       
        tHeader.map((v) => { str += v + ',' })
        str += '\n';

        list.map((v) => {
          filterVal.map((j) => {
            if (j == "Balance") {
              str += v[j] / 100 + '元'+ + '\t,';
            } else if (j == "UploadTime") {
              str += v[j].substring(0, 10) + '/' + v[j].substring(11, 18)+ + '\t,';
            } else {
              str += v[j]+ + '\t,';
            }
          })
          str += '\n';
        })


        var blob = new Blob([str], {
          type: "text/plain;charset=utf-8"
        });
        //解决中文乱码问题
        blob = new Blob([String.fromCharCode(0xFEFF), blob], {
          type: blob.type
        });
        var object_url = window.URL.createObjectURL(blob);
        var link = document.createElement("a");
        link.href = object_url;
        link.download = "明细表.csv";
        document.body.appendChild(link);
        link.click();
        document.body.removeChild(link);
      },