function jsonValue() {
    function jsonObject() {
      var o = {}, t = state.tokens.next;
      advance("{");
      if (state.tokens.next.id !== "}") {
        for (;;) {
          if (state.tokens.next.id === "(end)") {
            error("E026", state.tokens.next, t.line);
          } else if (state.tokens.next.id === "}") {
            warning("W094", state.tokens.curr);
            break;
          } else if (state.tokens.next.id === ",") {
            error("E028", state.tokens.next);
          } else if (state.tokens.next.id !== "(string)") {
            warning("W095", state.tokens.next, state.tokens.next.value);
          }
          if (o[state.tokens.next.value] === true) {
            warning("W075", state.tokens.next, "key", state.tokens.next.value);
          } else if ((state.tokens.next.value === "__proto__" &&
            !state.option.proto) || (state.tokens.next.value === "__iterator__" &&
            !state.option.iterator)) {
            warning("W096", state.tokens.next, state.tokens.next.value);
          } else {
            o[state.tokens.next.value] = true;
          }
          advance();
          advance(":");
          jsonValue();
          if (state.tokens.next.id !== ",") {
            break;
          }
          advance(",");
        }
      }
      advance("}");
    }

    function jsonArray() {
      var t = state.tokens.next;
      advance("[");
      if (state.tokens.next.id !== "]") {
        for (;;) {
          if (state.tokens.next.id === "(end)") {
            error("E027", state.tokens.next, t.line);
          } else if (state.tokens.next.id === "]") {
            warning("W094", state.tokens.curr);
            break;
          } else if (state.tokens.next.id === ",") {
            error("E028", state.tokens.next);
          }
          jsonValue();
          if (state.tokens.next.id !== ",") {
            break;
          }
          advance(",");
        }
      }
      advance("]");
    }

    switch (state.tokens.next.id) {
    case "{":
      jsonObject();
      break;
    case "[":
      jsonArray();
      break;
    case "true":
    case "false":
    case "null":
    case "(number)":
    case "(string)":
      advance();
      break;
    case "-":
      advance("-");
      advance("(number)");
      break;
    default:
      error("E003", state.tokens.next);
    }
  }
Parse input according to the JSON format.

http://json.org/