So I wrote this fs function to read files data from a file:
const fs = require("fs");
const read = function (file) {
fs.readFile(file, "utf8", (err, data) => {
if (err !== null) {
throw err;
}
console.log(data);
callback(data);
});
};
Now I am trying to write a function that will basically take two different files in txt that contains numbers for example:
files.txt content would have the numbers:
2 3 4 5
files2.txt content would have the numbers:
5 6 2 7
Where I am confused is implementing the function to get the sum of both files
const sumTheFiles = function (file1, file2){
let num1 = read(file1)
let num2 = read(file2)
let sum = num1 + num2
return sum
}
Can I get some advice on this on how I would tackle this. I have no idea what to do I am currently stuck
Thanks!
The best way would be to use fs.promises instead, so you can Promise.all.
const sumTheFiles = function (file1, file2){
Promise.all([file1, file2].map(
filename => fs.promises.readFile(filename, 'utf-8')
)
.then(([result1, result2]) => {
// do stuff with file content result1 and result2
})
.catch(handleErrors); // don't forget this part
};
If you have to use the callback versions, you can assign to an outside variable, and check if the other one is populated.
const sumTheFiles = function (file1, file2){
let r1;
let r2;
read(file1, (data) => {
r1 = data;
if (r2) finish();
});
read(file2, (data) => {
r2 = data;
if (r1) finish();
});
const finish = () => {
// do stuff with r1 and r2
};
}
I found the solution after playing with the way the fs.readFile was position in the code. All I did was repeat the fs.readFile
const sumTheFiles = function(file1, file2, callback) {
fs.readFile(file1, "utf8", (err, data) => {
if (err) {
callback(err, null);
} else {
let num1 = data;
fs.readFile(file2, "utf8", (err, data) => {
if (err) {
callback(err, null);
} else {
let num2 = data;
const sum = Number(num1) + Number(num2);
callback(null, sum);
}
});
}
});
};