Making a star triangle using javascript function recursively

Question

I am pretty new to programming, I am getting to know JavaScript, and I've just learned the notion of recursion. Now I am given a problem, to create a function (like const f = function(n) { }) and if we if we call the function with f(5), we should see:

     *
    ***
   *****
  *******
 *********

The number of vertical stars must be determined by the input. I've got to use no for/while/do-while; recursion only to loop.

I've come up with this code to concatenate 5 stars

const f = function(n) {
  if (n === 0) {
    return "";
  }
  return  "*" +  f(n - 1);
};

 console.log(f(5));

Though, I don't see how to make the triangle, what can I do?

Answer 1

You can use this code:

const f = function(chr, n) {
  if (n === 0) {
    return "";
  }
  return  chr +  f(chr, n - 1);
};
const g = function(max) {
   const inner = function(n) {
       if (n > 1) {
           inner(n-1);
       }
       console.log(f(' ', max-n) + f('*', (n*2)-1));
   };
   inner(max);
};
g(5);