Why appear undefined in the end of for-loop in JavaScript when I try to prints out layers of stars?

Question

I try to write a function called "stars" which prints out layers of stars in the following pattern:

stars(1);
// *
stars(4);
// *
// **
// ***
// ****

this is my code:

function stars(n){
   let result="";
   for(let i=1;i<=n;i++){
    result +="*" ;
    console.log(result);
     }
}
console.log(stars(1));
console.log(stars(4));

but, it turns out to be:

"*"
undefined

"*"
"**"
"***"
"****"
undefined

I try to take apart the loop but still can't figure out why the "undefined" appeared. Thanks!

Answer 1

You should just call stars(x),Instead of using console.Because your function doesn't return anything?