actually, let me make it faster against big functions ^_^ ```js const isClass = (fn) => typeof fn === 'function' && /^class /.test(isClass.toString.call(fn)); ```
On Thu, Jan 19, 2017 at 12:46 PM, Andrea Giammarchi < [email protected]> wrote: > If you are looking for isClass or similar you can also rely on > `Function.prototype.toString` decompilation, which is de facto consistent. > > ```js > const isClass = (fn) => > typeof fn === 'function' && > !isClass.toString.call(fn).indexOf('class '); > ``` > > Of course if you transpile code, including classes, that'd be useless (but > then you'll have many other problems anyway) > > Best Regards > > > On Thu, Jan 19, 2017 at 12:18 PM, Isiah Meadows <[email protected]> > wrote: > >> Inline. >> >> On Thu, Jan 19, 2017, 03:26 Claude Pache <[email protected]> wrote: >> >>> Le 17 janv. 2017 à 23:48, Isiah Meadows <[email protected]> a >>> écrit : >>> >>> Out of curiosity, why are classes specified to have a [[Call]] internal >>> method instead of special-casing `typeof` and friends to work with them? >>> Somewhat of a tangent, but just a curious question on the design decision. >>> >>> I guess that class constructors could have been specified without a >>> [[Call]] internal method, with the cost of amending all the places where >>> “constructible” implicitly implies “callable”. >>> >> >> FWIW, calling methods that don't have [[Call]] already throws a >> TypeError. So it wouldn't affect necessarily all sites, especially if you >> continue to check for [[Call]] in `Array.prototype.forEach` (like what is >> currently done), etc. >> >> But why (and how) do you need “special-casing `typeof` and friends”? (The >>> way the question is formulated, avoiding special-casing would be an >>> argument for the current design. But I miss what are the special cases you >>> have in mind, especially regarding `typeof`.) >>> >> >> I was specifically referring to `typeof (class {}) === "function"`. The >> "and friends" was in reference to things like the callback in >> `Array.prototype.forEach`, which IIUC doesn't currently throw for classes >> if the array has no members. >> >> Sorry for the poor phrasing there. >> >> >>> —Claude >>> >> >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss >> >> >
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