Welcome there,
I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.
You can also use the “preformatted text” tool in the editor (</>) to add backticks around text.
See this post to find the backtick on your keyboard.
Note: Backticks (`) are not single quotes (').
It looks as though you have a lot more logic than needed. The hint is in the test user-story:
…can be successfully parsed by
new Date(date_string)
That is, if this operation succeeds:
new Date(input)
Then, you do not need to return Invalid Date.
Hope this helps