Creating and writing to files in Node.js

September 2, 2019

objectives:

have an input area
create a file and write to it

what we need to know:

file system api fs
events api events

Example code which is getting some data from a file, converting it, and then saving it to another file:

code

const data = require("./data");
const fs = require("fs");
const EventEmitter = require("events").EventEmitter;
const fileEvents = new EventEmitter();

// console.info('All data', data)

let mappedComments = [];

data.map((object) => {
  // only get objects where there are comments
  if (object["og_object"].hasOwnProperty("comments")) {
    let comments = object["og_object"]["comments"]["data"]; // array of objects, should be ~70 results

    comments.map((item) => {
      let commentEntry = {
        comment_author_email: "info@forcespenpals.co.uk",
        comment_author: item.from.name,
        comment_author_url: "https://facebook.com/" + item.from.id,
        comment_content: item.message,
        comment_date: item.created_time,
        comment_date_gmt: item.created_time,
        comment_approved: 1,
        comment_post_title: object.title,
        comment_post_id: object.og_object.id,
        user_id: 2,
      };
      // console.info(commentEntry)
      mappedComments.push(commentEntry);
    });
  }
});
// console.info('Comments', mappedComments)

// Write the results (in JSON format) to a file
// you need to JSON.stringify() the data you save. otherwise the file will have everything saved as [object][object]
fs.writeFile("comments.json", JSON.stringify(mappedComments), (err) => {
  if (err) throw err;
  console.info("File is created successsfully");
});