Bad order of .entries() method

I have this code and need help (question in the end).

Basically the code has two lists, both lists contain numbers, and I need to add them in order. For example: first number in list 1 plus first number in list 2. Please do not recommend other solutions, because it’s the only path I have to take, it’s a simplified version of a harder task. So doing math here is just an example to run code.

const fs = require("fs");

const pathToTheListOneFile = "./list1.txt"
const pathToTheListTwoFile = "./list2.txt"


const list1 = fs.readFileSync(pathToTheListOneFile).toString().split("\n");
const list2 = fs.readFileSync(pathToTheListTwoFile).toString().split("\n");


console.log(list1)
console.log(list2)

for (const [index1, number1] of list1.entries()) for (const [index2, number2] of list2.entries()) {

    if (number1.includes("(processed) ") && number2.includes("(processed) ")) {
        console.log(`[${index1}][${index2}] Skipping ${number1} and ${number2} as has been processed before`);
        continue;
    }

    console.log(`[${index1}] [${index2}] Adding ${number1} to ${number2}`);

    const output = number1 + number2;

    if (output.stderr && output.code !== 0) {
        throw new Error(
            `[${index1}] ${index2}] Failed to add ${number1} to the ${number2} ` +
            `last '${"(processed)" + list1[index1] && list2[index2]}'`
        )
    }

    list1[index1] = "(processed) " + list1[index1]
    list2[index2] = "(processed) " + list2[index2]

    fs.writeFileSync(pathToTheListOneFile, list1.join("\n"));
    fs.writeFileSync(pathToTheListTwoFile, list2.join("\n"));

    console.log(`[${index1}][${index2}] Adding ${number1} to ${number2} has been successful\n\n`);
}


const notDone = list1.find((i) => !i.includes("(processed)"));
if (notDone) {
    console.log("Adding didn't process, re-run")
    return;
}

console.log("Adding has been successful!")

And this is running result:

[ '3', '4', '5' ]
[ '2', '3', '4' ]
[0] [0] Adding 3 to 2
[0][0] Adding 3 to 2 has been successful


[0] [1] Adding 3 to 3
[0][1] Adding 3 to 3 has been successful


[0] [2] Adding 3 to 4
[0][2] Adding 3 to 4 has been successful


[1] [0] Adding 4 to (processed) 2
[1][0] Adding 4 to (processed) 2 has been successful


[1] [1] Adding 4 to (processed) 3
[1][1] Adding 4 to (processed) 3 has been successful


[1] [2] Adding 4 to (processed) 4
[1][2] Adding 4 to (processed) 4 has been successful


[2] [0] Adding 5 to (processed) (processed) 2
[2][0] Adding 5 to (processed) (processed) 2 has been successful


[2] [1] Adding 5 to (processed) (processed) 3
[2][1] Adding 5 to (processed) (processed) 3 has been successful


[2] [2] Adding 5 to (processed) (processed) 4
[2][2] Adding 5 to (processed) (processed) 4 has been successful


Adding has been successful!

So the question is: how can I make it work in order only? I mean like this:

[0] [0]
[1] [1]
[2] [2]
[3] [3]
[4] [4]
[5] [5]

and skip other unnecessary additions like

[0] [1] or [2] [1]

>Solution :

You are making a nested for-loop. What you need is a single for-loop instead

for (let i = 0; i < list1.length && i < list2.length; i++) {
    let number1 = list1[i];
    let number2 = list2[i];
    //do your stuff...
}