I meant `true` for those - I had my conditions flipped. My bad. -----
Isiah Meadows [email protected] www.isiahmeadows.com On Thu, Feb 14, 2019 at 8:55 AM Andrea Giammarchi <[email protected]> wrote: > > > 1. If `value` is either `null` or `undefined`, it gracefully falls back to > > `false` instead of throwing an error. > > I am having hard time logically thinking of an empty void as false: > > Object.isEmpty(void 0) is false ? > > I think keys(o || {}).length === 0 is a more explicit, ambiguity free, > alternative. > > isEmpty(null) === false when typeof null is still object also doesn't feel > too right. > > > On Thu, Feb 14, 2019 at 7:31 AM Isiah Meadows <[email protected]> wrote: >> >> This would be roughly equivalent to `Object.keys(value).length === 0`, >> but with a few exceptions: >> >> 1. If `value` is either `null` or `undefined`, it gracefully falls >> back to `false` instead of throwing an error. >> 2. It takes enumerable symbols into account, like `Object.assign`. >> >> So more accurately, it returns `false` if the value is neither `null` >> nor `undefined` and has an own, enumerable property, or `true` >> otherwise. >> >> It's something I sometimes use when dealing with object-based hash >> maps (like what you get from JSON, input attributes). I typically fall >> back to the (partially incorrect) `for ... in` with a `hasOwnProperty` >> check for string keys, but I'd like to see this as a built-in. >> >> There's also a performance benefit: engines could short-circuit this >> for almost everything with almost no type checks. It's also an obvious >> candidate to specialize for types. >> >> - If it's not a reference type (object or function), return `true`. >> - If it's not a proxy object, or a proxy object that doesn't define >> `getPropertyDescriptor` or `ownKeys`, it's often just a memory load, >> even with dictionary objects and arrays. >> - If it's a proxy object with `ownKeys` and/or >> `getOwnPropertyDescriptor`, this is the slow path, but you can still >> short-circuit when `ownKeys` returns an empty array. >> >> ----- >> >> Isiah Meadows >> [email protected] >> www.isiahmeadows.com >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
