3 ms·

Subtle readability improvements on patterns that see extensive use actually make a difference. I had the exact same thoughts when `.includes()` was proposed to

by johnfn 5y ago

Subtle readability improvements on patterns that see extensive use actually make a difference. I had the exact same thoughts when `.includes()` was proposed to be added to the spec - it's just `.indexOf() !== -1`! - but time has proven me wrong, and I suspect it will prove us wrong about `at` as well. I've written an `.indexOf() !== -1` check hundreds if not thousands of times, and I've gotten the conditional wrong enough times to actually need to revert a change in prod. I have similar thoughts about .at(). Taking an element from the end of the array is ever-so-slightly error prone. Sure, you won't make a mistake this time, or the next time, but write it a hundred times, or a thousand, and I bet a bug will slip in. It's darn near impossible to get `.at(-1)` wrong, however.

beaconstudios 5y ago
That's actually a pretty reasonable argument, the 'length - N' form is actually quite prone to off-by-one errors so .at might help there.
NicolaiS 5y ago
Indeed, and as others have stated it is really hard to allow `[-1]` without breaking old code. Also: `[1, NaN, "hi"].indexOf(NaN)` is -1 but `.includes(NaN)` returns true as expected.
- nawgz 5y ago
  > `[1, NaN, "hi"].indexOf(NaN)` is -1 but `.includes(NaN)` returns true Brutal.
alerighi 5y ago
Except you would never get to use this method, because it will take years for all browser vendors to implement it, and even then, you still have a number of users that use for a reason or another Internet Explorer. You need to use a transpiler (like Typescript), but at this point, there no reason to implement that in the language, a transpiler can implement the feature by simply adding the method to the prototype of the object, like this: Array.prototype.at = function (i) { return i < 0 ? this[this.length + i] : this[i] }

3 ms·

Subtle readability improvements on patterns that see extensive use actually make a difference. I had the exact same thoughts when `.includes()` was proposed to

by johnfn 5y ago

beaconstudios 5y ago
That's actually a pretty reasonable argument, the 'length - N' form is actually quite prone to off-by-one errors so .at might help there.
NicolaiS 5y ago
Indeed, and as others have stated it is really hard to allow `[-1]` without breaking old code. Also: `[1, NaN, "hi"].indexOf(NaN)` is -1 but `.includes(NaN)` returns true as expected.
- nawgz 5y ago
  > `[1, NaN, "hi"].indexOf(NaN)` is -1 but `.includes(NaN)` returns true Brutal.
alerighi 5y ago
Except you would never get to use this method, because it will take years for all browser vendors to implement it, and even then, you still have a number of users that use for a reason or another Internet Explorer. You need to use a transpiler (like Typescript), but at this point, there no reason to implement that in the language, a transpiler can implement the feature by simply adding the method to the prototype of the object, like this: Array.prototype.at = function (i) { return i < 0 ? this[this.length + i] : this[i] }