JS has had switch statements for a long time. Do you mean switch "expressions" that can be used inline? It's not pretty but JS has long supported that too using either eval() "hacks" or IIFEs: https://stackoverflow.com/questions/32451049/is-eval-the-onl...
Do you mean pattern matching? There are two Stage 1 TC39 proposals with different approaches to it:
There are several libraries with strong Iterator support today that while not syntactically gorgeous do great jobs at allowing you to write simple list operations. Off the top of my head are IxJS and iter-tools, but also classic mainstays like up to date versions of lodash and Ramda.
That ship has probably sailed. Most projects at this point just have linter rules to standardize everything to the more reliable "triple equals" (===, and !==).
JS has had switch statements for a long time. Do you mean switch "expressions" that can be used inline? It's not pretty but JS has long supported that too using either eval() "hacks" or IIFEs: https://stackoverflow.com/questions/32451049/is-eval-the-onl...
Do you mean pattern matching? There are two Stage 1 TC39 proposals with different approaches to it:
More hands-on/direct: https://github.com/tc39/proposal-pattern-matching
More indirect: https://github.com/tc39/proposal-do-expressions
> list comprehensions
There are several libraries with strong Iterator support today that while not syntactically gorgeous do great jobs at allowing you to write simple list operations. Off the top of my head are IxJS and iter-tools, but also classic mainstays like up to date versions of lodash and Ramda.
There's a Stage 2 proposal to bring more of them into "the standard library": https://github.com/tc39/proposal-iterator-helpers
There's also a Stage 2 proposal for an operator to make the syntax generally nicer no matter the library: https://github.com/tc39/proposal-pipeline-operator
> array slicing
Array.prototype.slice() was added back in ES2015: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...
Array.prototype.at() was "just added" in ES2022 for unary (single argument) "slice" (ability to use negative indexes): https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...
If you prefer syntax to function calls, there's a Stage 1 proposal still live for that: https://github.com/tc39/proposal-slice-notation
> better equality operators
That ship has probably sailed. Most projects at this point just have linter rules to standardize everything to the more reliable "triple equals" (===, and !==).
There are proposals for more structural equality functions in the standard library, though, for instance: https://github.com/tc39/proposal-array-equality