how to store use triple-quoted backtick strings with marked.js

I’m using marked.js to render code that we want to store (ultimately as JSON). However, the I can’t get triple-back-ticked convention to render correctly. I’m sure user error on my part but how would I to get the following to work?

<script src="https://cdn.jsdelivr.net/npm/marked/marked.min.js"></script>
<div id="content"></div>
<script>
let str = marked.parse("here is the body of arguments ```\n\nclass User\n  def say_my_name\n  puts 'my name'\n  end\nend```");
document.getElementById('content').innerHTML = str;
</script>

which renders for me like:

>Solution :

What you have is

here is the body of arguments ```

class User
 def say_my_name
 puts 'my name'
 end
end```

But that is not valid. The code fences should always be on a new line:

let str = marked.parse("here is the body of arguments \n```\n\nclass User\n  def say_my_name\n  puts 'my name'\n  end\nend\n```");
document.getElementById('content').innerHTML = str;

<script src="https://cdn.jsdelivr.net/npm/marked/marked.min.js"></script>
<div id="content"></div>