JSON.parse should be simple and idiot-proof

Peter Jaszkowiak p.jaszkow at gmail.com
Sun Oct 21 19:59:14 UTC 2018


What if `JSON.parse` took an options object as the second parameter?
There's already been an instance of a JS API changing from booleans to an
options object: `addEventListener`.

I know it wasn't tc39, but it shows that it's possible. Another option is
to add a different method to the `JSON` object.

On Sun, Oct 21, 2018, 13:45 Richard Gibson <richard.gibson at gmail.com> wrote:

> Yes, understood. And setting aside the undesirable characteristics of boolean
> trap <https://ariya.io/2011/08/hall-of-api-shame-boolean-trap> interfaces
> for the moment (which will certainly be a source of regret if ECMAScript
> ever gets a BigFloat), my point is that doing so would affect parsing of
> *all* numbers, as opposed to only those numbers that really should be
> BigInts. For example, let's look at a sample Twitter API entity
> <https://developer.twitter.com/en/docs/tweets/data-dictionary/overview/tweet-object>
> :
>
> { "created_at":"Thu Apr 06 15:24:15 +0000 2017", "id": 850006245121695744,
> "id_str": "850006245121695744", "text": "1/ Today we’re sharing our vision
> for the future of the Twitter API platform!nhttps://t.co/XweGngmxlP",
> "user": { "id": 6253282,
> "id_str": "6253282",
> "name": "Twitter API",
> "screen_name": "twitterapi",
> "followers_count": 21,
> "friends_count": 32 }, "entities": {} }
>
>
> It's nice that e.g. JSON.parse(…, null, true) would allow us to access
> the ids as full-fidelity numbers (Twitter documents them as an int64), but
> much less nice that the behavior would affect all numbers. For instance,
> let's say this is one tweet in a list that we want to sort by the "follower
> ratio" of their creators:
>
> let creatorPopularity = tweet.user.followers_count /
> tweet.user.friends_count;
>
> // (without parse-as-BigInt) → 0.65625
>
> // (with parse-as-BigInt)    → 0n
>
>
> We just silently lost floating-point arithmetic.
>
> On Sun, Oct 21, 2018 at 1:00 PM Isiah Meadows <isiahmeadows at gmail.com>
> wrote:
>
>> This would be the correct understanding here, a 4th parameter read as a
>> boolean.
>>
>> On Sun, Oct 21, 2018 at 12:27 Peter Jaszkowiak <p.jaszkow at gmail.com>
>> wrote:
>>
>>> He was recommending a single parameter for "parse ints as bigints", not
>>> changing the default behavior.
>>>
>>> On Sun, Oct 21, 2018, 09:58 Richard Gibson <richard.gibson at gmail.com>
>>> wrote:
>>>
>>>> First, note that reviver functions *do* manipulate the result after
>>>> it's parsed. Second, "parse ints as bigints" is too big a hammer—changing
>>>> the output for all numbers would break currently working code. And third,
>>>> it's not even fully sufficient for the "big numbers" purpose, which
>>>> logically also includes non-integers outside the IEEE 754 64-bit range
>>>> ("BigFloat").
>>>>
>>>> On Sun, Oct 21, 2018 at 10:50 AM Isiah Meadows <isiahmeadows at gmail.com>
>>>> wrote:
>>>>
>>>>> Just because something exists doesn't mean it'll be  broadly used.
>>>>> Plus, reviver functions are normally incredibly simple - you don't get
>>>>> enough context (like key paths) to do anything crazy, and this proposal
>>>>> doesn't give you enough context for that.
>>>>>
>>>>> In practice, this changes literally nothing for most consumers, since
>>>>> the use case is incredibly limited and usually requires server agreement as
>>>>> well. In fact, that's where my skepticism lies: why add 3 new reviver
>>>>> parameters when a single "parse ints as bigints" would solve basically the
>>>>> entire problem? I've yet to see any other use case that couldn't be solved
>>>>> by manipulating the result after it's parsed.
>>>>>
>>>>> But personally, I don't see how bugs would be a major issue here
>>>>> considering its limited utility.
>>>>>
>>>>> On Sun, Oct 21, 2018 at 02:01 kai zhu <kaizhu256 at gmail.com> wrote:
>>>>>
>>>>>> wish to express skepticism for the stage-1 proposal "JSON.parse
>>>>>> source text access" [1], from web-integration perspective.
>>>>>>
>>>>>> a common javascript-painpoint is pinpointing bug-source of end-to-end
>>>>>> client<->server communications.  thankfully, JSON.parse is rarely suspect
>>>>>> in this process.  this proposal however, encourage developers to introduce
>>>>>> bugs/doubts-of-reliability to JSON.parse, making integration bug-hunting
>>>>>> more painful than it already is.
>>>>>>
>>>>>> standard-operating-procedure for reviving JSON-data is a 2-step
>>>>>> process:
>>>>>> 1. JSON.parse with zero-config to rule-out bugs during this step
>>>>>> 2. second-pass of plain-JSON to revive [product-specific]
>>>>>> string-encoded non-JSON datatypes like BigInt/Date/RegExp, where
>>>>>> bugs can be expected
>>>>>>
>>>>>> you normally do not want to complicate bug-hunts by contaminating
>>>>>> step-1 with bugs from step-2.
>>>>>>
>>>>>> [1] stage-1 proposal - JSON.parse source text access
>>>>>> https://github.com/gibson042/ecma262-proposal-JSON-parse-with-source
>>>>>>
>>>>>> kai zhu
>>>>>> kaizhu256 at gmail.com
>>>>>>
>>>>>>
>>>>>>
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