For the serialization thing, take a look at jsonl.grammar.js. It's the file that gets passed to jison (a node package) to create jsonl.js and jsonl.min.js. I've modified it to copy the standard JSON example, but it still doesn't work. I think it would be best to forgo jsonl altogether and just use the standard JSON.parse().
Also, you can press shift+enter to enter a newline.