errmsg bad digit "\" while parsing port 30000 code 93

I ran into the same issue on Pluralsight's: "Introduction to MongoDb" tutorial. Below is what I used in the "configuring a replica set" section:

{
    "_id": "demo",
    "members": [
        {
            "_id": 0,
            "host": "localhost:30000",
            "priority": 10
        },
        {
            "_id": 1,
            "host": "localhost:40000"
        },
        {
            "_id": 2,
            "host": "localhost:50000",
            "arbiterOnly": true
        }
    ]
}

Solved it! Just removed all the spaces in between the javascript code and it ran fine.

I just removed space between localhost: and port number (localhost:30000) and the same thing for other 2 hosts. It worked fine.