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Version: 1.0

Downloading files

To share a download you call .downloadBuffer() or .download() on the file object:

// Using promises
const data = await file.downloadBuffer()

// data is a Buffer containing the file contents
console.log(data)

// Using callbacks
file.downloadBuffer((error, data) => {
  if (error) console.error(error)
  console.log(data)
})

Like when uploading, you need to use the I/O functions provided by your JavaScript platform to save data to disk, like fs.writeFile and Deno.writeFile.

If you use .download() then you can also download files using Node.js streams either via pipes...

const stream = file.download()
stream.on('error', error => console.error(error))
stream.pipe(fs.createWriteStream(file.name))

... or by listening data events:

const stream = file.download()
stream.on('error', error => console.error(error))
stream.on('data', data => console.log(data))
stream.on('end', () => console.log('finished'))

Those are useful when dealing with huge files as .downloadBuffer() stores the entire file in memory. In the other hand, because of that, .download() can't return a promise. Also, you can still use callbacks with .download() like in V0.

Despite .download() returning Node.js streams they still work in other platforms and you can it use with other libraries that work in browsers and expect Node.js streams as inputs, like the streamsaver library. Other option is listening to the data and end events and pass data from those events to the I/O functions from your platform, like the Deno.open function.

You can get progress events from the progress event like this:

const stream = file.download()
stream.on('progress', info => {
  console.log('Loaded', info.bytesLoaded, 'bytes of', info.bytesTotal)
})

In order to render the values returned by the progress event you have many options:

You can download shared files by loading those from their URL instead of loading from the Storage class:

import { File } from 'megajs'

// Get the file object from the URL
const file = File.fromURL('https://mega.nz/file/example#example')

// Load file attributes
await file.loadAttributes()

// Then finally download the file like usual
const data = await file.downloadBuffer()
console.log(data)

When deploying to browsers use file.api.userAgent = null to not set an user-agent since it will cause CORS issues on browsers that allow the user-agent header to be set (like Firefox).

Shared files loaded using File.fromURL don't have attributes - such as name and size - loaded by default, that's why loadAttributes is called. If you don't need those attributes, just file contents, you can download the file directly using .download():

// Will download the data without having to load attributes
const data = await File.fromURL('https://mega.nz/file/example#example').downloadBuffer()
console.log(data)

Shared folders can also be loaded using File.fromURL and will behave like folders in Storage: once their attributes are loaded they will have a .children property with an array of File objects which can be downloaded.

// Get the folder object from the URL
const folder = File.fromURL('https://mega.nz/folder/example#example')

// Load folder attributes
await folder.loadAttributes()

// Download a file from the folder
const file = folder.children.find(file => file.name === 'hello-world.txt')
const data = await file.downloadBuffer()
console.log(data)

When opening shared folders in MEGA you can right-click some file and get a file pointing to a specific file in the folder. This library recognizes those kind of links and allow loading the file specified. To make it work get the file from the promise, like this:

// Get the folder object from the URL
const folder = File.fromURL('https://mega.nz/folder/example#example/file/example')

// Load the file from the folder specified by /file/example in the URL
const file = await folder.loadAttributes()

// And download it
const data = await file.downloadBuffer()
console.log(data)

Like V0 .loadAttributes() will still accept a callback. The file specified by the URL will be returned in the second argument:

folder.loadAttributes((error, file) => {})

The download function also allows using a custom handleRetries function:

await file.download(
  handleRetries: (tries, error, cb) => {
    if (tries > 8) {
      // Give up after eight retries
      cb(error)
    } else {
      // Wait some time then try again
      setTimeout(cb, 1000 * Math.pow(2, tries))
    }
  }
}).complete

You can replace the default retry handling function by overriding File.defaultHandleRetries like this:

import { File } from 'megajs'

File.defaultHandleRetries = (tries, error, cb) => {
  if (tries > 8) {
    // Give up after eight retries
    cb(error)
  } else {
    // Wait some time then try again
    setTimeout(cb, 1000 * Math.pow(2, tries))
  }
}

The function in File.defaultHandleRetries is also the default function used by upload().

The last part of the tutorial is handling interrupted downloads.