[feature-request]: Async iterable streams on web streams

[jimmywarting]

What

Working with streams on either web streams or node streams are troublesome. cuz they are inconsistent with each other.
Therefore ppl resort to a more lower level syntax that works for both node:stream and web streams with the help of async for loop and Symbol.asyncIterators

for await (const item of readable) {
  console.log(item)
}

Making another transformation to the stream is easy too. just need to do:

/** 
 * @param {ReadableStream | node.Readable} iterable 
 */
async function * toUpperCase(iterable) {
  for await (const item of readable) yield item.toUppercase()
}

for await (const item of toUpperCase(readable)) {
  console.log(item)
}

NodeJS, deno, and web streams polyfill and the spec have this Symbol.asyncIterator
but non of the browser have this and there are a few tickets on this on their part.

I just wish for there to be a polyfill / patch in this missing feature, so that we can start using it. (not neccessary have to include the hole stream polyfill.

if (typeof ReadableStream !== 'undefined' && !ReadableStream.prototype[Symbol.asyncIterator]) {
  ReadableStream.prototype[Symbol.asyncIterator] = function () {
    const reader = this.getReader()
    let last = reader.read()
    return {
      next () {
        const temp = last
        last = reader.read()
        return temp
      },
      return () {
        return reader.releaseLock()
      },
      throw (err) {
        this.return()
        throw err
      },
      [Symbol.asyncIterator] () {
        return this
      }
    }
  }
}