It looks like your quote characters might be messed up there? Anyway, to parse json on the command line one should just use jq.

Single quotes were modified by HN engine, right. It is not a command line (thinking of sed?), it is the middle of a source code in my editor. I have a json-parsed message and t is a target object.

  a b foo c

  t.a = !!message.a;
  t.b = String(message.b);
  t.foo = message.foo;
  t.c = tonum(message.c);