RegExp /\c/ in JavaScript

Question

RegExp /\c/ doesn't trigger any syntax error.

console.log(/\c/)

The question is why it's not a syntax error. Since the language spec, I'm guessing Pattern → Disjunction → Alternative → Term → Atom → \ AtomEscape → CharacterEscape → IdentityEscape, then it arrives at SourceCharacter but not c and it doesn't match by the condition but not c.

https://www.ecma-international.org/ecma-262/8.0/#sec-regular-expressions-patterns

I wonder if I'm wrong.

Answer 1

I found it.

The \c doesn't match to \ AtomEscape alternative. This was correct. So the \ letter matches to ExtendedPatternCharacter and the c letter matches to ExtendedPatternCharacter individually.

/^\x$/.test("x") //→ true
/^\c$/.test("c") //→ false
/^\c$/.test("\\c") //→ true