I'm trying to do a function with JS and nodejs to create a .json file with my MongoDB data in it.

But when I run my function my console show me

Uncaught TypeError: Cannot read property 'prototype' of undefined.

I've done some research and my console that writeJsonFile's value is an object with no value, I don't know if it's the cause of my problem

json(event){ 
 count = Subs.find({}).count();
  var json;
  var obj;
  Subs.find({}).forEach(function (div) {
    var sub_type = div.type;
    var sub_TO = div.text;
    var man = div.topic;
    obj = {[man]: []};
    obj[man].push({"type": sub_type, "TO": sub_TO});
    json = JSON.stringify(obj);
    const writeJsonFile = require('write-json-file');

    writeJsonFile('foo.json', {foo: true}).then(() => {
      console.log('done');
    });
    console.log(json);
  });
}

I'm trying to do a function with JS and nodejs to create a .json file with my MongoDB data in it.

But when I run my function my console show me

Uncaught TypeError: Cannot read property 'prototype' of undefined.

I've done some research and my console that writeJsonFile's value is an object with no value, I don't know if it's the cause of my problem

json(event){ 
 count = Subs.find({}).count();
  var json;
  var obj;
  Subs.find({}).forEach(function (div) {
    var sub_type = div.type;
    var sub_TO = div.text;
    var man = div.topic;
    obj = {[man]: []};
    obj[man].push({"type": sub_type, "TO": sub_TO});
    json = JSON.stringify(obj);
    const writeJsonFile = require('write-json-file');

    writeJsonFile('foo.json', {foo: true}).then(() => {
      console.log('done');
    });
    console.log(json);
  });
}

• javascript
• json
• node.js
• mongodb
• reactjs

• On what line do you get this error? And do you still get the error if you remove all code above the json writing part? – Jerodev Commented Nov 27, 2017 at 15:07
• Where do you get this error ? In the writeJsonFile function whose code you don't show ? – Denys Séguret Commented Nov 27, 2017 at 15:07
• @Jerodev the error came at the line const writeJsonFile = require('write-json-file'); and if i remove the code above i still have the problem – alpheonix Commented Nov 27, 2017 at 15:16
• Is write-json-file a third party module, or something you've written in the same folder as that JS code? – Andy Commented Nov 27, 2017 at 15:22
• @Andy write-json-fileis a npm install module that i found here [link] (github./sindresorhus/…) – alpheonix Commented Nov 27, 2017 at 15:27

1 Answer 1

Better you use fs module of nodejs. No need to install it.

Here simple example of writing data to JSON file.

const fs = require('fs');
json = {
    one: 1,
    two: 2
}
json = JSON.stringify(json);
fs.writeFile('./foo.json', json, (err) => {
    if (!err) {
        console.log('done');
    }
});