I tried to add a new section to identify if not rock paper scissors


And I don't know what my mistake.

if(userChoice=rock paper scissors);{}
else{confirm("choose just rock or paper or scissors")};


In the link
read about
comparison operators
logical operators

An IF statement looks

if ( condition ) {
   //IF code-block

Javascript will try to evaluate the given condition(s) to a Boolen true or false

If you want to combine multiple comparisons as a condition
you will have to use so-called logical operators

For instance
the condition

userChoice != "paper" && userChoice != "rock" && userChoice != "scissors"

would be read as

userChoice not equal "paper" AND userChoice not equal "rock" AND userChoice not equal "scissors"