How to properly add setInterval/setTimeout to my function

Question

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'));

See: [How to create a typing effect](https://www.w3schools.com/howto/howto_js_typewriter.asp) — Yogi, Jun 06 '22 at 08:27

MickyDore · Answer 1 · 2022-06-06T08:50:23.550

0

function printLetters(start, finish) {  
  //should add checks here to validate start comes before finish 

  console.log(start)
  if (start == finish) {
    return
  }
  else {
   setTimeout(printLetters, 1000, String.fromCharCode(start.charCodeAt(0)+1), finish)
  }
}

printLetters('a', 'f')

edited Jun 06 '22 at 08:50

answered Jun 06 '22 at 08:39

MickyDore

146
6

score 0 · Accepted Answer · answered Jun 06 '22 at 08:41

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');

https://codepen.io/lmntrix029/pen/oNEMPVM – Kent Vincent Dela Cruz Jun 06 '22 at 08:43 — Kent Vincent Dela Cruz, Jun 06 '22 at 08:43

score 0 · Answer 3 · answered Jun 06 '22 at 08:46

Here is a solution using an async sleep function.

function sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
}
async function alphabet(from,to){
  var currentLetter = from[0];
  while(currentLetter.charCodeAt(currentLetter[0]) != to.charCodeAt(to[0])+1){
    let l = currentLetter
    await sleep(1000)
    console.log(l)
    nextLetter = String.fromCharCode(currentLetter.charCodeAt(currentLetter[0])+1)
    currentLetter = nextLetter;
  }
}
alphabet('A','F');

How to properly add setInterval/setTimeout to my function

3 Answers3