What is function createServer(requestListener?: RequestListener):server?

I am new to NodeJS.
I am not very familiar with this statement:function createServer(requestListener?: RequestListener):server. Why does this method have :server, and why are the parameters inside not separated by commas, but uses ?:?

Any ideas on how to fix this problem

191 thoughts on “What is function createServer(requestListener?: RequestListener):server?”

  1. Excellent goods from you, man. I have understand your stuff
    previous to and you’re just too fantastic. I actually like what
    you have acquired here, certainly like what you are
    stating and the way in which you say it. You make it enjoyable
    and you still take care of to keep it sensible. I can not wait to read much more from you.

    This is actually a terrific website.

    Reply
  2. I simply couldn’t leave your site prior to suggesting that I actually enjoyed the usual info a person supply for
    your visitors? Is gonna be back regularly in order to check up on new posts

    Reply
  3. I’ve been browsing on-line more than 3 hours as
    of late, yet I never found any attention-grabbing article like yours.
    It is pretty value sufficient for me. In my view, if all
    site owners and bloggers made excellent content material
    as you did, the web will be a lot more helpful than ever before.

    Reply
  4. Hey! I know this is kinda off topic however I’d figured I’d ask.
    Would you be interested in exchanging links or maybe guest
    authoring a blog post or vice-versa? My website covers a lot
    of the same topics as yours and I feel we could greatly benefit from each other.
    If you happen to be interested feel free to shoot me an email.
    I look forward to hearing from you! Fantastic blog by the way!

    Reply
  5. I love your blog.. very nice colors & theme. Did you create this website yourself
    or did you hire someone to do it for you? Plz respond as I’m looking
    to construct my own blog and would like to find out where u got this from.
    kudos

    Reply
  6. Heya are using WordPress for your blog platform?

    I’m new to the blog world but I’m trying to get started and create my own. Do you require any coding expertise to
    make your own blog? Any help would be really appreciated!

    Reply