csvToJson.js

csvToJson.js

const fs = require('fs');


let reader = fs.createReadStream('books.csv', 'utf8');
let writer = fs.createWriteStream("books.json");

let result= [];
let index = null;
let data = '';
reader.on('data', (chunk) =>{
    data += chunk
})
reader.on('end',  ()=>{
    //slpit into array of strings 
     data = data.split(/\r\n/);
    //get rid off first row and split each item into array of  [ title, author, description] 
    data =  data.slice(1).map(i => i.split(';'))

    for (let i = 0; i < data.length; i++) {
        //check if author already in list
        index = result.findIndex(item => item.author === data[i][1]);
        //if not add author and books
        if(index === -1){
        result.push({
                 author: data[i][1], 
                 books:[{  
                    title: data[i][0],
                    description:data[i][2]
                        }]
            })            
        //else add book info to existing author's books array
        }else{
            result[index].books.push(
                {
                    title: data[i][0],
                    description:data[i][2]
                })
        }
    }

    writer.write(JSON.stringify({authors:result}))
    
})