.size option not supported on res.body

It’s not mentioned in the README that when using res.body and not res.json() etc, that the .size option will not trigger any response size limiting errors.

[jimmywarting]

As an attempt to implement nodes new stream-consumers then this became more apparent to me. Right now i feel like removing size option all together. it’s not part of the spec and it is not implemented in any other fetch implementation.

[jimmywarting]

Here is my take on looking at the size limit in a cross platform way-ish and looking at download progress at the same time

const ctrl = new AbortController()
const limit = 1024
const res = await fetch(url, { signal: ctrl.signal })
const knownLength = Number(res.headers.get('content-length') || 0)
const notEncoded = !res.headers.get('content-encoding')
const decoder = new TextDecoder()
let responseText = ''
let bytesWritten = 0


if (knownLength > limit) {
  ctrl.abort()
  throw new Error(`content size at ${res.url} over limit`)
}

for await (const chunk of res.body) {
  bytesWritten += chunk.byteLength
  if (bytesWritten > limit) {
    ctrl.abort()
    throw new Error(`content size at ${res.url} over limit`)
  }
  if (notEncoded && knownLength) {
    console.log(`progress = ${bytesWritten / knownLength}`)
  }

  // Do something else with chunk
  responseText += decoder.decode(chunk, { stream: true })
}

responseText += decoder.decode() // flush the remaning bytes
const json = JSON.stringify(responseText)