I've been trying to do some html and css but I'm really bad at this so far. I was using a function that would check if two selectors match. A friend of mine came up with this code but neither of us fully understands how the return of the "tag.class" case works. My question is, if it doesn't divide the newSelector, how can it succesfully check the tag and class?

var matchFunctionMaker = function(selector) {
  var selectorType = selectorTypeMatcher(selector);
  var matchFunction;
  if (selectorType === "id") { 
    matchFunction = nuevoSelector => '#' + nuevoSelector.id === selector;
  } else if (selectorType === "class") {
    matchFunction = nuevoSelector => {
      var lista = nuevoSelector.classList;
      for (let x of lista) {
        if (selector === '.' + x) return true;
      }
      return false;
    } 
  } else if (selectorType === "tag.class") {
    matchFunction = nuevoSelector => {
      var [tag, clase] = selector.split('.');
      return matchFunctionMaker(tag) (nuevoSelector) && matchFunctionMaker(`.${clase}`) (nuevoSelector);
    };
  } else if (selectorType === "tag") {
    matchFunction = nuevoSelector => nuevoSelector.tagName.toLowerCase() === selector.toLowerCase();
  }
  return matchFunction;
};

Thanks in advance!