Untitled

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body>

<script id="jsbin-javascript">
function dd(t){ console.log("dd: ", t);}

for (let i=1; i<=3; i++) {
  console.log("first loop: ", i);
  setTimeout(function() {console.log(i);}, 1000);
}

for (let i=1; i<=3; i++) {
  console.log("2nd loop: ", i);
  setTimeout(() => {dd(i);}, 2000);
}

let s;
for (let i=1; i<=3; i++) {
  console.log("3rd loop: ", i);
  s=i.toString();
  setTimeout(() => {dd(s);}, 2000);
}
</script>


<script id="jsbin-source-javascript" type="text/javascript">function dd(t){ console.log("dd: ", t);}

for (let i=1; i<=3; i++) {
  console.log("first loop: ", i);
  setTimeout(function() {console.log(i);}, 1000);
}

for (let i=1; i<=3; i++) {
  console.log("2nd loop: ", i);
  setTimeout(() => {dd(i);}, 2000);
}

let s;
for (let i=1; i<=3; i++) {
  console.log("3rd loop: ", i);
  s=i.toString();
  setTimeout(() => {dd(s);}, 2000);
}
</script></body>
</html>