JSON.parse should be simple and idiot-proof

Richard Gibson richard.gibson at gmail.com
Sun Oct 21 19:45:17 UTC 2018


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
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> es-discuss mailing list
>>>>> es-discuss at mozilla.org
>>>>> https://mail.mozilla.org/listinfo/es-discuss
>>>>>
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