Yeah, I'm aware. I'm keeping my previous "prototype with a specific method" this time around. Much easier IMHO.
On Tue, Jan 24, 2017, 13:47 Claude Pache <[email protected]> wrote: > > > Le 24 janv. 2017 à 19:12, Isiah Meadows <[email protected]> a > écrit : > > > > To clarify, I'm wanting to know if it's a callable that isn't a class. > > Technically, I could use `Function.prototype.toString` for most > > practical purposes of mine, but that'd be super slow (I'd need it in a > > warm loop), and wouldn't catch native construct-only classes like `Map` > > and `Set` (which are still `typeof f === "function"`). > > > > ```js > > var funcToString = Function.prototype.toString > > > > function isCallable(f) { > > return typeof f === "function" && > > /^\s*class(\s*\{|\s+[^(])/.test(funcToString.call(f)) > > } > > ``` > > Your `isCallable` function has a flaw: it will treat differently: > > ```js > // ES6 class > class Foo { > constructor() { > // ... > } > } > ``` > > and: > > ```js > // pre-ES6 almost-compatible approximation of a class > function Foo() { > if (!(this instanceof Foo)) > throw new TypeError("Foo must be invoked with 'new'"); > // ... > } > ``` > > You are unable to guess that a function defined with the `function` > keyword is intended to be a constructor or a function. > > —Claude
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