https://github.com/antlr/grammars-v4/blob/master/javascript/javascript/JavaScriptParser.g4
grammars-v4/javascript/javascript/JavaScriptParser.g4 at master · antlr/grammars-v4
Grammars written for ANTLR v4; expectation that the grammars are free of actions. - antlr/grammars-v4
github.com
ecmascript 6 bnf