FOR LOOP in Node js needing the result of the previous iteration - node.js

Question

I need to do a loop in Node JS where I need the result of the previous iteration.
function jsonParser(txt_file, cb) {
var perc = 0;
lines = txt_file.split('\n');
insert_communication = 'INSERT INTO communication (account_id, contact_id, type_com_id, coin_id, com_datetime, ' +
'destination_key, destination_st, duration, cost, description, discount) VALUES ';
insert_internet = 'INSERT INTO internet_data (account_id, contact_id, type_com_id, coin_id, com_datetime, ' +
'duration, cost, description, discount) VALUES ';
for (let i = 2; i < lines.length; i++) {
readTextFile2(lines[i], function (cb) {
if (cb[0] == "communication")
insert_communication += cb[1] + ',';
if (cb[0] == "internet")
insert_internet += cb[1] + ',';
});
}
cb(insert_communication);
}
How I am supposed to achieve this?
Thanks

Answer 1

for (let i = 2; i < lines.length; i++) {
const previous = lines[i - 1 ];
const hasPrevious = !!previous;
if(hasPrevious) {
//ok you have a previously value, now you could use it
}
readTextFile2(lines[i], function (cb) {
if (cb[0] == "communication")
insert_communication += cb[1] + ',';
if (cb[0] == "internet")
insert_internet += cb[1] + ',';
});
}