Return value from recurring function

Question

This Meteor server recursive method commonHint returns result undefined to the console even the finalRes has a value.
Any suggestion o

Answer 1

Any place you call commonHint you need to return the value of the call.

  ... 

  if (!hinters) {
    hinters = [...lib.getCombinations(['arg1', 'arg2', 'arg3'], 2, 3)];
    return this.commonHint(doc, shortMatches, hinters, results);  // hinters is an array of length 3 with 2 elements each
  }

  ...

  if (hinters.length > 0) {
    return this.commonHint(doc, shortMatches, hinters, results);

Answer 2

Every path out of a recursive function that returns a result must return a result. In yours, you have paths that don't: When hinters isn't provided, and when hinters.length > 0 is true.

You should return the result of the recursive call:

  if (!hinters) {
    hinters = [...lib.getCombinations(['arg1', 'arg2', 'arg3'], 2, 3)];
    return this.commonHint(doc, shortMatches, hinters, results);  // hinters is an array of length 3 with 2 elements each
//  ^^^^^^
  }

  // ...

  if (hinters.length > 0) {
    return this.commonHint(doc, shortMatches, hinters, results);
//  ^^^^^^
  } else {
    let finalRes = lib.mostCommon(results);
    console.log(finalRes);  //<==== has a value
    return finalRes;        //<==== so return it to caller
  }