what is the error

// Getting input via STDIN

const readline = require("readline");

const inp = readline.createInterface({

input: process.stdin

});

inp.on("line", (data) => {

const inputstring=data.toString();

let line ="";

for( i=0, a=inputstring.length; i<a;i++)

line+=inputstring[i] +","

{

console.log(line);

}

//end-here

});