I honestly wouldn't worry about this edge case - it's rare you actually would want to serialize symbols, and it's usually best handled at the application level, not the framework level.
On Mon, Nov 13, 2017, 06:10 Alex Vincent <[email protected]> wrote: > In modern ECMAScript, objects can have symbols for property names instead > of strings. This leads me to a problem in my es7-membrane project: how do > I translate those symbol keys into JSON for a reusable file? (I partially > answer my own question below.) > > Consider the following code: > > const X = {}; > const two = Symbol("two"); > Reflect.defineProperty(X, "one", {value: 1, writable: true, enumerable: > true, configurable: true}); > Reflect.defineProperty(X, two, {value: 2, writable: true, enumerable: > true, configurable: true}); > return JSON.stringify(Reflect.ownKeys(X)); > > In both Mozilla Firefox and Google Chrome, this returns ["one", null]. I > suppose this is part of the ECMAScript's latest standard. I do see > JSON.stringify has a "replacer" callback argument, and JSON.parse has a > "reviver" argument. I presume that these are here to solve > encoding/decoding problems with JSON. This may be the route I take... > > At first, serializing shouldn't be a problem: if I hit a symbol as a key, > I could use the replacer functionality to deliver a standard > JSON-serializable object. > > But what if the ordering of keys is not guaranteed? I'm referring > specifically to the case of a developer modifying X's properties in the > above snippet - say, by defining Symbol("three") as a key before the two > key. Or worse, by defining a different Symbol("two") before the existing > two key? I am not referring to the case of the developer modifying the > results from Result.ownKeys(). > > Now, all of a sudden, this little stringify problem has possibly morphed > into a diff/merge problem: between yesterday's serialized JSON for ownKeys > and today's, someone has cleverly inserted a symbol where there was another > in the list of keys. My code is supposed to infer today from yesterday's > generated JSON which property key belongs to which property value. With > symbols - especially identically-keyed symbols - I could lose that > consistency if I'm not careful. > > (Side note: for es7-membrane, I faced a similar but easily solvable > problem, where Reflect.ownKeys(function() {}) returned different results in > different browsers - especially when the function passed into ownKeys had > additional properties. In that case all the properties were strings, so I > just extracted the common set of string-named properties and put them at > the front of the keys list for consistency.) > > I'm looking for advice - including the very real possibility that I'm > overthinking this or worrying too much about an edge case. > > -- > "The first step in confirming there is a bug in someone else's work is > confirming there are no bugs in your own." > -- Alexander J. Vincent, June 30, 2001 > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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