Functions containing dollar signs ($) are incorrectly fixed

[renato-bohler]

Description

While validating this plugin against a big codebase, I found an edge case where it auto-fixes incorrectly.

If the function has a dollar sign ($) on its body, it gets incorrectly transformed somehow.

Example 1

export function foo() {
  const bar = '$';
  return bar
};

Gets transformed into an invalid syntax. Notice the lack of the dollar sign, the missing single quote, and the extra semicolon at the end:

export const foo = () => {
  const bar = ';
  return bar
};;

Example 2

If the dollar sign is in backticks:

export function foo() {
  const bar = `$`;
  return bar
};

Then this happens:

export const foo = () => {
  const bar = `(PARAMS)RETURN_TYPE => ;
  return bar
};;

(PARAMS)RETURN_TYPE => is leaking from the writeArrowFunction function somehow

eslint-plugin-prefer-arrow-functions/src/prefer-arrow-functions.ts

Lines 137 to 146 in 9b76409

	const writeArrowFunction = (node) => {
	const { body, isAsync, isGeneric, generic, params, returnType } =
	getFunctionDescriptor(node);
	return 'ASYNC<GENERIC>(PARAMS)RETURN_TYPE => BODY'
	.replace('ASYNC', isAsync ? 'async ' : '')
	.replace('<GENERIC>', isGeneric ? generic : '')
	.replace('BODY', body)
	.replace('RETURN_TYPE', returnType ? returnType : '')
	.replace('PARAMS', params.join(', '));
	};

Example 3

If there are two dollar signs, then the transformation is different, but still incorrect:

export function foo() {
  const bar = `$$`;
  return bar
};

And this happens:

export const foo = () => {
  const bar = `const foo = ;
  return bar
};;

Suggested Solution

No idea why that happens, so I'd have to investigate. Probably need to escape $ when replacing or something?

Help Needed

I just need time to look into that.

[JamieMason]

haha wow, this is an interesting one.