JavaScript identifier handling: differences to spec

[gandaro]

The code for JavaScript identifiers:

markdown-rs/src/util/identifier.rs

Lines 5 to 17 in 1506572

	/// Check if a character can start a JS identifier.
	#[must_use]
	pub fn id_start(char: char) -> bool {
	UnicodeID::is_id_start(char) || matches!(char, '$' | '_')
	}
	/// Check if a character can continue a JS (or JSX) identifier.
	#[must_use]
	pub fn id_cont(char: char, jsx: bool) -> bool {
	UnicodeID::is_id_continue(char)
	|| matches!(char, '\u{200c}' | '\u{200d}')
	|| (jsx && char == '-')
	}

... has some issues:

1. It does not seem to recognize the literal string \u1234 or \u{1234} (see UnicodeEscapeSequence production in ECMAScript) as a valid character in starting/continuing characters—though I am not sure if this is the case; you might convert such instances to Unicode characters beforehand, I do not know.
2. It does not recognize "$" within a JS identifier (see IdentifierPartChar production in ECMAScript).
3. I don't know why you allow U+200C and U+200D in id_cont; those are not "special" in the productions I looked at in JSX or ECMAScript.

[wooorm]

This looks like a theoretical issue. Are you actually running into a problem? The code here is JSX-focused.