On Fri, Sep 8, 2017 at 2:28 AM, Alex Kodat <[email protected]> wrote: > Head slap. The following does what I want with essentially zero > overhead (at least with V8)...
:-) Clever solution for situations where you can't detect these statically in advance, nice one. You can turn it up to 11 by avoiding hitting the proxy for the `Object.property` properties, by making the base guard prototype derive from your proxy and put the `Object.property` features on it. That way, `hasOwnProperty`, `valueOf`, etc. aren't impacted by passing through the proxy. (See my `Guarded` below.) https://jsperf.com/throw-on-missing-property-scenarios You'll also want to handle `toJSON` and other spec-defined optional properties or properties implementations commonly look for outside spec (is that what your `inspect` property is?). And set `constructor`. ```js function Guarded() { } Guarded.prototype = Object.create(new Proxy(Object.freeze(Object.create(null)), { get: (target, prop) => { if (prop === "toJSON" || prop === "inspect") { return undefined; } throw Error("Bad property: " + prop); } })); Object.defineProperties(Guarded.prototype, Object.getOwnPropertyDescriptors( Object.prototype)); Object.defineProperty(Guarded.prototype, "constructor", { value: Guarded, configurable: true }); class Foo extends Guarded {} ``` -- T.J. Crowder
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