sebmck/6to5

// @flow
import {
  isIdentifierName,
  isStrictReservedWord,
  isKeyword,
} from "@babel/helper-validator-identifier";

/**
 * Check if the input `name` is a valid identifier name
 * and isn't a reserved word.
 */
export default function isValidIdentifier(
  name: string,
  reserved: boolean = true,
): boolean {
  if (typeof name !== "string") return false;

  if (reserved) {
    if (isKeyword(name) || isStrictReservedWord(name)) {
      return false;
    } else if (name === "await") {
      // invalid in module, valid in script; better be safe (see #4952)
      return false;
    }
  }

  return isIdentifierName(name);
}