How to make this simple javascript code work?

PeterBushMan · March 14

i=0;
for (i=0; i<100; i++)
{ document.write(".");
setTmeout( null,100);
}
</script>
</body>
</html>

I want to print 100 dots, after one dot, rest 0.1 second.

I do NOT use to use the statement "setTimeout(function, s)";

I want to set the function to null, but it does NOT work, how to make it work as the function is null.

Endy0816 · March 14

Was a typo, setTimeout is missing an 'i'.

I think you do need to have it call a function though.

Edited March 14 by Endy0816

pzkpfw · March 14

setTimeout is async, i.e. it's non-blocking and will never work like this. The for loop would race ahead and make 100 setTimeouts all at once, then they'd all fire at more or less the same time, not 100 ms after each other.

Also, Endy0816 is right that the null cannot be used. You do need to call a function, or have a string that evaluates to code, or use a lambda (arrow function).

This works:

<html>
<head></head>
<body>
<p>Test:</p>
<script>
let i = 100;
setTimeout(ShowDot, 100);

function ShowDot() {
  document.write(".");

  if (i-- > 1) {
    setTimeout(ShowDot, 100);
  }
}
</script>
</body>
</html>

If you want the first dot to show immediately, just replace the first:

setTimeout(ShowDot, 100);

With:

ShowDot();

See: https://developer.mozilla.org/en-US/docs/Web/API/setTimeout

Edited March 14 by pzkpfw

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