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File Downloading Progress Simulation

This project simulates file downloading with progress updates and intermittent connection interruptions. It demonstrates asynchronous JavaScript using Promises and setTimeout to mimic real-world file downloads.

Features:

  • Simulates multiple file downloads concurrently.

  • Shows progress updates at 10%, 50%, and 100%.

  • Randomly simulates connection interruptions and automatic retries.

  • Uses Promise.all to handle multiple downloads and detect overall completion or failure.

  • Provides clear success ✅ or failure ❌ messages.

Code Overview

  1. F1: Formula 1 Teams Data

let f1 = [ Formula 1 Teams for 2025 Season, {Team:"McLaren",Drivers:[{name:"Oscar Piastri",Car_number:81,from:"Australia"},{name:"Lando Norris",Car_number:4,from:"United Kingdom"}]}, {Team:"Ferrari",Drivers:[{name:"Charles Leclerc",Car_number:16,from:"Monaco"},{name:"Lewis Hamilton",Car_number:44,from:"United Kingdom"}]}, ... ];

  • This part stores data about Formula 1 teams and drivers.

  • Each team object contains the team name and an array of drivers.

  1. File Download Simulation

function fileDownload(file){ console.log(Preparing file to download...); let random = Math.floor(Math.random()*10);

return new Promise((resolve, reject) => {
    setTimeout(()=>{ console.log(`file is 10% downloaded...`); }, 100)
    setTimeout(()=>{ console.log(`file is 50% downloaded...`); }, 300)

    if(random < 6 && random > 3){
        setTimeout(()=>{ console.log("Connection is interrupted, retrying..."); }, 350)
        setTimeout(()=>{ console.log("Connected Download is resuming..."); }, 365)
    }

    setTimeout(()=>{
        if(random > 3){
            console.log(file + " has been 100% downloaded");
            resolve(`file is successfully downloaded: ` + file)
        } else {
            reject(new Error(`${file} Connection is lost, downloading is terminated. Try again later 😔😔`))
        }
    }, 600)
})

}

  • fileDownload(file) simulates downloading a single file.

  • It randomly determines if the download will fail or succeed.

  • Logs progress at different stages (10%, 50%, 100%).

  • Simulates connection interruptions with retry messages.

  1. Downloading Multiple Files

let f2 = fileDownload("file1") let f3 = fileDownload("file2") let f4 = fileDownload("file3") let f5 = fileDownload("file4")

Promise.all([f2, f3, f4, f5]) .then(() => console.log("✅ All downloads 100% completed.")) .catch(n => console.log("❌ At least one download failed " + n))

  • Downloads multiple files concurrently.

  • Promise.all waits for all downloads to finish.

  • Logs overall success or failure depending on individual downloads.

How to Run:-

  1. Copy the code into a JavaScript file (e.g., downloadSimulation.js).

  2. Open the file in Node.js terminal:

node downloadSimulation.js

  1. Watch the console for progress messages, connection interruptions, and final results.

Output Example Preparing file to download... file is 10% downloaded... file is 50% downloaded... Connection is interrupted, retrying... Connected Download is resuming... file1 has been 100% downloaded ❌ At least one download failed file2 Connection is lost, downloading is terminated. Try again later 😔😔 ✅ All downloads 100% completed.

Notes

  • This is a simulation; no actual files are downloaded.

  • The randomness simulates real-world unreliable network behavior.

  • Can be extended to handle retry logic automatically or add more progress steps