Please help with writing spec for async JSON APIs

[James M Snell]

On Mon, Aug 3, 2015 at 8:34 AM, Allen Wirfs-Brock <allen at wirfs-brock.com> wrote:
[snip]
>
> 4) JSON.parse/stringify are pure computational  operations.  There is no
> perf benefit to making them asynchronous unless some of their computation
> can be performed concurrently.
>

If we're speaking strictly about making the JSON parsing asynchronous,
then correct, there is really no performance benefit to speak of. You
may be able to offload the parsing to a separate thread, but it's
going to take the same amount of time. The real benefit will come when
(a) JSON parsing becomes incremental and (b) a developer is given
greater control over exactly how the JSON is converted to/from
strings.

Something along the lines of...

JSON.parser(input).
  on('key', function(key, context) {
    if (key === 'foo')
      console.log(context.value());
    else if (key === 'bar')
      context.on('key', ...);
  }).
  on('end', function() {
  });

In other words: allowing for incremental access to the stream and fine
grained control over the parsing process, rather than having to block
while everything is parsed out, building up the in-memory object
model, then being forced to walk that model in order to do anything
interesting.

Personally, I'm not overly concerned about the possibility of races.

- James