downloading file with node js

dl.js

const fs = require('fs')
const fetch = require("node-fetch")
const path = "C:\\DOWNLOADS\\";
const urlArray = [
    //["url","fileName"]
    //"url"
    //["url","filename"],"url",["url","filename"]
    
    "http://somesite.com/somevideo.mp4",
    ["http://somesite.com/somevideo2.mp4","renamedvideo.mp4"],
    ["http://google.com","google.html"],
];

//## Downloading the files
//## either one file at the time

// startDownloading(urlArray, 1);

//## or X files at a time

startDownloading(urlArray, 4);



async function startDownloading(array, count = 1){
    const splitLinksArray = [];

    array.forEach((list,i)=>{
        const array_index = i % count;
        if( !splitLinksArray[array_index] ) splitLinksArray[array_index] = [];
        splitLinksArray[array_index].push(list)
    })

    splitLinksArray.forEach((list,i)=>{
        downloadFromArray(list, i+1);
    })
}

async function downloadFromArray(array, index){
    for (let i = 0; i < array.length; i++) {
        await downloadFile( array[i], `${index}/${(i+1)}` );
    };
}

async function downloadFile(url, index){
    return new Promise(async (resolve, reject) => {
        let fileName = "";
        if(typeof url === "string"){
            fileName = url.match(/[^\/]+(?=\/$|$)/gi)[0];
            if(!/.mp4|.mp3|.jpg|.png|.gif|.gifv/gi.test(fileName)) fileName = url.replace(/[&\/\\#,+()$~%.'":*?<>{}]/g,'_') + ".html";
        }else{
            fileName = url[1];
            url = url[0];
        }

        if(fs.existsSync(path + fileName)) {
            console.log(`#${index}: ${fileName} => File already exists, skipping...`);
            resolve();
        }

        console.log(`#${index}: ${fileName} => DOWNLOADING...`);

        fetch(url).then(res => {
            const writeStream = fs.createWriteStream(path + fileName);
            res.body.pipe(writeStream);
            writeStream.on('close', () => {
                console.log(`#${index}: ${fileName} => File downloaded.`);
                resolve();
            });
            writeStream.on('error', (err)=> {
                console.log(`#${index}: ${fileName} => File system error => ${err}`);
                resolve();
            });
        }).catch(err=>{
            console.log(`#${index}: ${fileName} => URL error => ${err}`);
            resolve();
        });
    })
}