Count the total number of lines of xls exel files in directory

gistfile1.txt

var fs= require("fs");
var node_xj = require("xls-to-json");
var totalLines= 0;

fs.readdir('./FTA', function (err, files) {
    files.forEach((file,idx) => {
        console.log(file);
        node_xj({
          input: './FTA/'+file,  // input xls
          output: null // output json
        }, function(err, result) {
          if(err) {
            console.error(err);
        } else {
            let lines= result.length -1;
            totalLines+= lines;    // to not count the header.
            console.error(file+": "+lines+ " lines");
           
            if(idx == files.length-1 )  console.error("    "+totalLines); 
           }
        });
       
    });
})