Exported Module Returning Object Promise -- calling fs.readFile as a module

Question

I wrote a simple module that reads a file called readHistory.js:

const fs = require('fs');


async function readHistory(history){
    fs.readFile("history_file.txt", function read(err, data) {
        if (err) {
            throw err;
        }

    const myRAM = data.toString();
    history = myRAM;
    //console.log(myRAM); 
    });
};
readHistory();
module.exports = { readHistory }

I import it to a different module like so:

const { readHistory } = require("./readHistory")

Then I try to get the value like this:

const contextClues = Promise.resolve(readHistory(myRAM));

Which returns:

 [object Promise]

I also tried like this:

const contextClues = Promise.resolve(readHistory(myRAM));    
contextClues.then((value) => {
    console.log("Other context: " + value)
})

Which returned Undefined.

I've tried a bunch of different permutations on the above so I'm starting to think the problem is in ReadHistory.js.

I've tried putting my expression inside an async function and using await:

const contextClues = await Promise.resolve(readHistory(myRAM))

And that returns Undefined which I think is worse. I've tried writing the function with and without an argument and it doesn't seem to matter. To be honest the argument is an artifact from when I tried writing it as a callback but that didn't work either.

Alexander Nenashev · Accepted Answer · 2023-05-20T04:55:43.863

1

Moving a reading of a file to a separate module could be simplified with 1 line:

const fs = require('fs');
const history = fs.readFileSync('history_file.txt').toString();

edited May 20 '23 at 04:55

answered May 20 '23 at 03:57

Alexander Nenashev

8,775
2
6
17

I have a freshly upgraded node. I've been out of the game for a while but my environment is up-to-date. I've been getting up on ES Modules but I'm still more familiar with the CommonJS way for right now. The readfile script works on its own, it just doesnt work when I call it from the other module – Z-Man Jones May 20 '23 at 04:05
@Z-ManJones sorry man, your code doesn't make sense. It just wrong JS. I'm adding code how to make it in a module – Alexander Nenashev May 20 '23 at 04:08
It's part of a much larger file and I tried to trim it down to only the relevant parts. Maybe I overedited – Z-Man Jones May 20 '23 at 04:09
As you see you just move 1 code line to a module. For me it doesn't much improve the situation... – Alexander Nenashev May 20 '23 at 04:15
Even with those solutions, I still don't see how I extract the value from the readfile to perform operations – Z-Man Jones May 20 '23 at 04:30
1

`const history = fs.readFileSync('history_file.txt').toString();` - the simplest solution – Alexander Nenashev May 20 '23 at 04:37
That is....easy. Thank you. This was overengineered. If you post this as an answer I'll mark it solved. – Z-Man Jones May 20 '23 at 04:47
@Z-ManJones done and good luck with your project! – Alexander Nenashev May 20 '23 at 04:56

Exported Module Returning Object Promise -- calling fs.readFile as a module

1 Answers1