prefer-at should also mark substrings of length 1

[ST-DDT]

Description

The prefer-at rule should also check for substrings of length 1.

Fail

string.substring(0, 1)
string.substring(value, value + 1)
string.substring(value, 1 + value)
string.substring(value - 1, value)

Pass

string[0]
string[value]
string[value - 1]

or

string.at(0)
string.at(value)
string.at(value - 1)

And maybe:

string.charAt(0)
string.charAt(value)
string.charAt(value - 1)

Additional Info

No response

[fisker]

It's a good idea.

But we have a problem to add this rule.
We already have prefer-string-slice rule enforce users move to String#slice().

And we can't check foo.slice(0, 1), since foo can be an array or something else with .slice() unless we have type information.

[sindresorhus]

While not ideal, the common solution for this is to introduce an option to prefer-string-slice to ignore substrings of length 1.

[sindresorhus]

Accepted.

[ST-DDT]

While not ideal, the common solution for this is to introduce an option to prefer-string-slice to ignore substrings of length 1.

IMO there is no need for a new option, as slice is effectively a substring and thus should also use .charAt/at when possible.

EDIT: Oh I see.
Is there a way to give the prefer-at rule a higher priority than slice? So that it's fixers run first?

Because the option is prone to being configured wrong.
E.g. if it is enabled by default, but prefer-at is not, then it misses changes. If it is not enabled by default, then it is most likely forgotten during initial apply and thus all substrings of length 1 already use slice.

Edit2: Maybe this will end up with requiring type information anyway. 🤷