Have you ever encountered performance issue because of copying object on deserialization?
https://gist.github.com/Ginden/381448a17f50c7669b9a3693742e3a3d For me results are: Simple JSON.parse, 100000 iterations: 39.594999999997526ms JSON.parse with copy, 100000 iterations: 184.5699999999997ms JSON.parse with __proto__ change, 100000 iterations: 89.75500000000102ms On Wed, Sep 28, 2016 at 5:49 PM, 段垚 <[email protected]> wrote: > 在 2016/9/28 22:59, Danielle McLean 写道: > > From: 段垚 (mailto:[email protected]) >> Date: 28 September 2016 at 16:36:52 >> >> [I]mplementors warn that mutating prototype causes "performance >>> hazards". >>> >> You don't actually need to mutate any prototypes to get prototypeless >> objects out of `JSON.parse` - the reviver function is allowed to >> return a new object instead, so you can create a fresh one with the >> correct prototype. For example: >> >> ```js >> JSON.parse(string, function(k, v) { >> if (v && typeof v === 'object' && !Array.isArray(v)) { >> return Object.assign(Object.create(null), v); >> } >> return v; >> }); >> ``` >> > > Yes, but creating a copy also has performance penalty. This proposal is > made for performance. > > How about adding an option to omit prototype of objects created by >>> JSON.parse()? >>> >>> JSON.parse(str, { noPrototype: true }); >>> >> While you can achieve the appropriate result already without extra >> language support, I think this particular situation is common enough >> that such an option might be a good idea. >> >> How would you expect this new parameter to interact with the existing >> second parameter to `JSON.parse`, the reviver function? I'd suggest >> that the cleanest way to add the options would be for the second >> parameter to be either an object or function, like this: >> >> ```js >> JSON.parse(str, someFunc); >> // equivalent to >> JSON.parse(str, {reviver: someFunc}); >> ``` >> > Looks reasonable. > > Maybe we can simply add another method, say `JSON.parseWithoutPrototype()`. > This makes feature detection easier. > > > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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