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If I understand this correctly it is to add negative index support to arrays. How will findIndex work when this is introduced? It currently uses -1 as a return value when no element satisfies the testing function.
[1, 2, 3, 4].at(0) === 1
[1, 2, 3, 4].at(1) === 2
[1, 2, 3, 4].at(-1) === 4
findIndex’s behavior is unchanged.
If I understand this correctly it is to add negative index support to arrays. How will findIndex work when this is introduced? It currently uses -1 as a return value when no element satisfies the testing function.
So [0, 1, 2, 3].at(-2) === 2
So instead of fixing the language and allow to use array[-1], they add an other way to access array element. This is why I don't like JavaScript, instead of fixing feature, they add new feature to fix previous feature.
There is existing code out there which relies on negative indexes to return undefined. Or relies on being able to assign items to negative indexes and then retrieve them, this is perfectly valid code: `a=[];a[-1]=42;console.log('the answer is',a[-1])`. The web tries really hard to be backwards compatible and not break existing code.
So instead of fixing the language and allow to use array[-1], they add an other way to access array element. This is why I don't like JavaScript, instead of fixing feature, they add new feature to fix previous feature.
There is existing code out there which relies on negative indexes to return undefined. Or relies on being able to assign items to negative indexes and then retrieve them, this is perfectly valid code: `a=[];a[-1]=42;console.log('the answer is',a[-1])`. The web tries really hard to be backwards compatible and not break existing code.
But perhaps we just don't know enough, and they will add the `at`, and at some point actually do bind `arr[index]` to use the implementation of that function?
If I understand this correctly it is to add negative index support to arrays. How will findIndex work when this is introduced? It currently uses -1 as a return value when no element satisfies the testing function.
Earlier quoted context omitted.
New features are added to JavaScript very carefully to avoid breaking existing code on the web. The downside is you often end up with multiple ways to do the same thing, but there are ways to mitigate this, like using a linter to enforce using a modern subset of the language.
That's starting to sound an awful lot more like C++.
Earlier quoted context omitted.
There is existing code out there which relies on negative indexes to return undefined. Or relies on being able to assign items to negative indexes and then retrieve them, this is perfectly valid code: `a=[];a[-1]=42;console.log('the answer is',a[-1])`. The web tries really hard to be backwards compatible and not break existing code.
How about deprecating that for a few years then? Doesn't seem good to keep the behavior, given that it will also be confusing in the future. But perhaps we just don't know enough, and they will add the `at`, and at some point actually do bind `arr[index]` to use the implementation of that function?
Earlier quoted context omitted.
There is existing code out there which relies on negative indexes to return undefined. Or relies on being able to assign items to negative indexes and then retrieve them, this is perfectly valid code: `a=[];a[-1]=42;console.log('the answer is',a[-1])`. The web tries really hard to be backwards compatible and not break existing code.
How about deprecating that for a few years then? Doesn't seem good to keep the behavior, given that it will also be confusing in the future. But perhaps we just don't know enough, and they will add the `at`, and at some point actually do bind `arr[index]` to use the implementation of that function?
Instead, adding .at() allows having the new feature now, and in a way that's possible to polyfill for backwards compatibility.
If I understand this correctly it is to add negative index support to arrays. How will findIndex work when this is introduced? It currently uses -1 as a return value when no element satisfies the testing function.