Finding the differences between 2 files in nodejs - node.js

Question

I have 2 json files which have static data.
File A.json
{
"data": ["A","B","C","D"]
}
File B.json
{
"data":["A","B","C"]
}
Now I want find the difference between these two files.
I tried using this code to get files by its name
const express = require("express");
const jsonfile = require("jsonfile");
const app = express();
const fs = require("fs");
app.use(express.json());
const BASEPATH = "./data"
app.get("/api/v1/data/:name", async (req,res) => {
const fileName = req.params.name;
const filePath = `${BASEPATH}/${fileName}.json`
try {
const readData = await jsonfile.readFile(filePath);
res.status(200).json(readData);
}catch (e) {
res.status(404).send(e);
}
});
The URL is : localhost:3000/api/v1/data/A
To add data I used,
app.put("/api/v1/data",(req,res) => {
const fileName = req.body.name;
const data = req.body.data;
const filePath = `${BASEPATH}/${fileName}.json`
fs.exists(filePath, async exists => {
if(exists) {
try {
await jsonfile.writeFile(filePath,{data:data});
res.status(200).send();
}catch(e) {
res.send(500).json(e);
}
} else {
try {
await jsonfile.writeFile(filePath,{data:data});
res.status(201).send();
}catch(e) {
res.send(500).json(e);
}
}
})
});
Example of added data:
{ "name":"C", "data":["A","B","Z"]}
URL is: localhost:3000/api/v1/data

Answer 1

you can try like this,
app.get("/api/v1/data/diff", async (req,res) => {
try {
const file1 = req.query.file1;
const file2 = req.query.file2;
console.log(file1,file2)
if(file1 === undefined || file2 === undefined ) {
res.status(401).send("BAD REQUEST. SEND FILE NAMES");
return;
} else {
const filePath1 = `${BASEPATH}/${file1}.json`
const filePath2 = `${BASEPATH}/${file2}.json`
const file1Data = await jsonfile.readFile(filePath1);
const file2Data = await jsonfile.readFile(filePath2);
let difference = file1Data.data.filter(x => !file2Data.data.includes(x));
let difference2 = file2Data.data.filter(x => !file1Data.data.includes(x));
res.status(200).json({diff: [...difference,...difference2]});
}
}catch(e) {
res.status(500).json(e);
}
});
you have to use the url like : localhost:3000/api/v1/data/diff?file1=A&file2=B
the output will be
{
"diff": [
"D"
]
}