How to properly add setInterval/setTimeout to my function

Pls, help!

The function should print the letters "A" through "F" to the console, one letter per second.

The function works without setInterval/setTimeout.

// setInterval(alphabet, 1000, 'a', 'f');

function alphabet(from, to) {
  var a = [], i = from.charCodeAt(0), j = to.charCodeAt(0);
  for (; i <= j; ++i) {
    setInterval(() => {
      a.push(String.fromCharCode(i));
    }, 1000);
  }
  // return console.log(a);
  return a;
}

console.log(alphabet('a', 'f'));

>Solution :

You might wanna try this.
You can paste it on codepen

var a = [];
function alphabet(from, to) {
    console.log(a);
    setInterval(() => {
        var i = from.charCodeAt(0);
        var j = to.charCodeAt(0);
        for (; i <= j; ++i) {
          if(a.includes(String.fromCharCode(i))){
             
          }else{
            console.log(String.fromCharCode(i))
            a.push(String.fromCharCode(i));
            break;
          }
        }
    }, 1000);
  return a;
}

alphabet('a', 'f');