wkhtmltopdf Transform pdf mine

I used this tool to transfer the Vue page, and it was no problem at the beginning, until one day the leader asked me to add a function and added some code due to personal reasons.

               let  bankcode=  this.bill["values"]["t20"];
               let vbank="";
               let  bankJson={
                    "YH003":"中国银行",
                    "YH001":"中国工商银行",
                    "YH004":"中国建设银行",
                    "YH002":"中国农业银行",
                    "YH005":"交通银行"
                }

                if(bankcode&&bankJson[bankcode]){
                    vbank=bankcode&&bankJson[bankcode];
                    this.bill["values"]['t666']=vbank
                    this.bill["values"]['t1']=vbank
                }

Just add this line and it won’t work. Then I checked the documents for more than 4 hours and tested all the methods. In the end, I tested the code line by line, and I deleted only one line of code, let xxxxxxx.
Okay, the problem came out; this tool The declaration method that does not support es6 is replaced with var to solve