proposal-hashbang VS proposal-function-memo

Before ECMAScript 2023 (ES14), executing a JavaScript file directly from the command line required manually specifying the interpreter path in the first line of the module. This process could vary depending on the operating system and Node.js installation.ES14 standardizes the use of hashbangs (#!) in JavaScript modules, enabling direct execution without the need for explicit interpreter invocation. The hashbang syntax is a simple convention that indicates the interpreter to be used for executing a module. It consists of a shebang (#!) followed by the path to the interpreter and optionally any arguments. For a JavaScript file, the hashbang line typically includes the path to the Node.js executable.

https://github.com/tc39/proposal-hashbang has some details.

Hashbang Grammar

Hashbang Grammar: match de-facto usage in some CLI JS hosts that allow for #! Shebangs / Hashbang.

But if you just wanted to execute it directly then you could use a shebang because everything after the bang is interpreted and not the bang its self. Most js engines allow this in some form. Here is a proposal to standardize it. https://github.com/tc39/proposal-hashbang

Function.memo

https://github.com/tc39/proposal-function-memo

This might be relevant to this exact pattern

  const getThing = (async function (arg1, arg2) {

Function Memoization: Function memoization.