Develop Reference

How do I export this named function through module.exports?

I have a command file for a discord bot that contains the command and a piece of parsing logic contained within a function that I want to reuse within my index.js
// file: ./commands/scrumPrompt.js
// The function
const extractDeets = function (f, scrum) {
let items = [];
let re = new RegExp("(\n[ -]*" + f + ".*)", "g");
let replace = new RegExp("[ -]*" + f + "[ ]+");
for (const item of scrum.matchAll(re)) {
items.push(item[1].trim().replace(replace, ""));
}
return items;
};
// The actual command itself within the same file
module.exports = {
name: "scrum",
usage: `!scrum < followed by your message > as per Standup format - refer !show for showing the format`,
description: "Reply to standup prompt",
async execute(message, args) {
if (message.channel.type === "text") {
if (!args.length)
return message.reply(
"Please Provide your scrum as per the format in help menu !scrum < your message >"
);
else {
if (message.author.id !== -1) {
const client = new MongoClient(MONGO_URI);
try {
const database = client.db(DB_NAME);
const members = database.collection("members");
const query = { user_id: message.author.id };
const membersdetail = await members.findOne(query);
if (membersdetail !== null) {
// since this method returns the matched document, not a cursor, print it directly
//console.log("Adding Scrum for ", membersdetail.email);
let userscrum = args.splice(0).join(" ");
// Check if multiple !scrum commands are present in developer scrum message
if (userscrum.includes("!scrum") == false) {
// Expects notations of "-" to exist
let [f, e, b, o, bl] = ["f", "e", "b", "o", "x"];
let features = extractDeets(f, userscrum);
let enhancements = extractDeets(e, userscrum);
let bugs = extractDeets(b, userscrum);
let others = extractDeets(o, userscrum);
let blockers = extractDeets(bl, userscrum);
.
.
.
};
I want to keep the name of the function as extractDeets() itself so that it doesn't mess with the usage within the command as well. I'm not completely sure how to export it into the index.js because it's already kind of being imported here:
// Imports the command file + adds the command to the bot commands collection
for (const file of commandFiles) {
const command = require(`./commands/${file}`);
bot.commands.set(command.name, command);
}
I'm unsure of how to add the function as another import, maybe I should export it into another file and then import it from there? I'm not sure if that's possible or doable here. I've tried directly importing from here but then the command doesn't work, which is troublesome.

You can do it like this:
module.exports = { extractDeets };
Later, you can import it like this:
const { extractDeets } = require('../your_file');

How to print file path with directory Indentation Nodejs

Printing file path with directory indentation.
Input will be
[
"/root/html/file/a.html",
"/root/html/image/a.jpg",
"/root/html/file/b.html",
"/tmp/c.log"
]
Output needs to be like following,
- root
- html
- file
- a.html
- b.html
- image
- a.jpg
- tmp
- c.log
I couldn't find any solution. I guess it will be a recursive call with a tree structure. Any help would be appreciated.

You could map each file path of your input data into a simple tree-map structure and then recursively print this structure. Something like this (not tested and might still need to handle edge cases):
function processData(data) {
const separator = "/";
const tree = {};
data.forEach(element => mapPathToTree(tree, element.split(separator).filter(part => part)));
printTree(tree, 0);
}
function mapPathToTree(tree, pathParts) {
if (pathParts && pathParts.length <= 1) {
tree[pathParts[0]] = {};
return;
}
const currPart = pathParts[0];
let subTree = tree[currPart];
if (!subTree) {
subTree = {};
tree[currPart] = subTree;
}
mapPathToTree(subTree, pathParts.slice(1));
}
function printTree(subTree, level) {
for (const key in subTree) {
console.log(" ".repeat(level).concat("- ").concat(key));
printTree(subTree[key], level + 1);
}
}
processData([
"/root/html/file/a.html",
"/root/html/image/a.jpg",
"/root/html/file/b.html",
"/tmp/c.log"
]);

csvtojson node.js (combine two codes)

How to combine these two codes, so it doesn't just covert csv to Json (first code), but also save this as an json array in an extra file?(second code)
this (first) code converts csv file to json array:
const fs = require("fs");
let fileReadStream = fs.createReadStream("myCsvFile.csv");
let invalidLineCount = 0;
const csvtojson = require("csvtojson");
csvtojson({ "delimiter": ";", "fork": true })
.preFileLine((fileLineString, lineIdx)=> {
let invalidLinePattern = /^['"].*[^"'];/;
if (invalidLinePattern.test(fileLineString)) {
console.log(`Line #${lineIdx + 1} is invalid, skipping:`, fileLineString);
fileLineString = "";
invalidLineCount++;
}
return fileLineString
})
.fromStream(fileReadStream)
.subscribe((dataObj) => {
console.log(dataObj);
// I added the second code hier, but it wirtes the last object of the array (because of the loop?)
}
});
and this (second) code saves the json array to an external file:
fs.writeFile('example.json', JSON.stringify(dataObj, null, 4);
The quistion is how to put the second codes into the first code (combine them)?

You can use .on('done',(error)=>{ ... }) method. (csvtojson). Push the data into a variable in subscribe method and write the data as JSON in .on('done'). (test was successful).
Check it out:
let fileReadStream = fs.createReadStream("username-password.csv");
let invalidLineCount = 0;
let data = []
csvtojson({ "delimiter": ";", "fork": true })
.preFileLine((fileLineString, lineIdx)=> {
let invalidLinePattern = /^['"].*[^"'];/;
if (invalidLinePattern.test(fileLineString)) {
console.log(`Line #${lineIdx + 1} is invalid, skipping:`, fileLineString);
fileLineString = "";
invalidLineCount++;
}
return fileLineString
})
.fromStream(fileReadStream)
.subscribe((dataObj) => {
// console.log(dataObj)
data.push(dataObj)
})
.on('done',(error)=>{
fs.writeFileSync('example.json', JSON.stringify(data, null, 4))
})

Not sure if you are able to change the library but I would definitely recommend Papaparse for this - https://www.npmjs.com/package/papaparse
Your code would then look something like this:
const fs = require('fs'), papa = require('papaparse');
var readFile = fs.createReadStream(file);
papa.parse(readFile, {
complete: function (results, file) {
fs.writeFile('example.json', JSON.stringifiy(results.data), function (err) {
if(err) console.log(err);
// callback etc
})
}
});

Read lines of a txt file and organize in a JSON file

I have a text file where each line is separated into 4 categories by colons and I want to put this into a JSON file, where each category is a value to the corresponding name in the JSON file.
Example data.txt file:
Date1:cat1:dog1:bug1
Date2:cat2:dog2:bug2
Date3:cat3:dog3:bug3
Example JSON file:
{
"Date1": {
"cat": "cat1",
"dog": "dog1",
"bug": "bug1"
},
"Date2": {
"cat": "cat2",
"dog": "dog2",
"bug": "bug2"
...
...
}
I've never used JSON before but I think that's how to format it. How would I sort each line using the colons as markers for the next value and store it in the JSON file with the correct name using JavaScript and Node.js?

Use the csv package if you don't want to handle parsing csv file by yourself.
const fs = require("fs");
const csv = require("csv");
const result = {};
const keys = ["cat", "dog", "bug"]
// Read data
const readStream = fs.createReadStream("yourfile.txt");
// Parser
const parser = csv.parse({ delimiter: ":" });
parser.on("data", (chunk) => {
result[chunk[0]] = {};
for(let i = 1; i < chunk.length; i ++) {
result[chunk[0]][keys[i - 1]] = chunk[i];
}
});
parser.on("end", () => {
console.log(result);
});
readStream.pipe(parser);

If your JSON has this defined structure you can go about it with the following code:
import * as fs from 'fs';
/* If you have a large file this is a bad Idea, refer to reading from a stream
* From zhangjinzhou's answer
*/
const file = fs.readFileSync('path/to/data.txt', 'utf8');
const json = file.split(/\n|\r\n/).map(line => {
const values = line.split(":");
let obj = {}
obj[values[0]] = {
cat: values[1],
dog: values[2],
bug: values[3],
};
return obj
}).reduce((acc, current) => Object.assign(acc, current), {})

Using RegExp and Array#forEach, convert the string to lines, then iterate over them and fill up the object with the corresponding data via:
const dataFileContent =
`Date1:cat1:dog1:bug1
Date2:cat2:dog2:bug2
Date3:cat3:dog3:bug3`;
function processData(data) {
// convert to lines
const lines = data.match(/[^\r\n]+/g) || [];
const object = {};
// iterate over the lines
lines.forEach(line => {
const parts = line.split(':');
const main = parts.shift();
const pattern = /^(.*?)(\d+)$/;
// create an object for each main part
object[main] = {};
// fill each main part with the sub parts
parts.forEach(part => {
const match = part.match(pattern) || [];
const key = match[1];
const value = match[2];
if (match) {
object[main][key] = key + value;
}
});
});
return object;
}
const processedData = processData(dataFileContent);
console.log(processedData);
Then convert the processedData to JSON by using JSON.stringify and save it to a file via:
const fs = require('fs');
...
// processData
...
const json = JSON.stringify(processedData);
fs.writeFile('my_json_file.json', json, 'utf8');
For larger files, consider using Streams in Node.js as suggested by #zhangjinzhou.

How to assign value as a function to an object without quotes?

I'm trying to generate very large Javascript files with node. Each one of them contains a const variable which assists for right values at the file (which I can know their values only on runtime). Example:
'use strict'
const lib = require('myLib')
const language = lib.getMyLang()
module.exports = {
"type": lib.getType(language),
"info": lib.getInfo(language),
"title": lib.getTitle(language)
}
When I've tried to generate it, I got the values as strings:
'use strict'
const lib = require('myLib')
const language = lib.getMyLang()
module.exports = {
"type": "lib.getType(language)",
"info": "lib.getInfo(language)",
"title": "lib.getTitle(language)"
}
The whole script is really large, this specific part I did like:
object[key] = "lib.getType(language)";
How can I generate the files right and not as strings?

try this
const test = require('./myLib');
const lang = test.language;
const obj = {};
for (const key in test) {
if (typeof test[key] == 'function') {
let tempKey = key.toLocaleLowerCase().replace('get', '')
obj[tempKey] = test[key](lang)
}
}
module.exports = obj;