Why is this simple JavaScript stopwatch not working?

Question

I wrote some very simple code the should represent a stopwatch with two buttons where clicking 'Start' should start counting upwards from 0 with 1 second delay.

However, when I click nothing changes. Where is my mistake?

"use strict";
var s = 1;

function mf() {
  setInterval(function() {
    document.getElementById("#sw").innerText = ++s;
  }, 1000);
}

<div id="sw">0</div>
<input type="button" value="Start" name="start" onlick="mf" />
<input type="button" value="Stop" name="stop" />

You need to call your function onclick. `onclick="mf"` should be `onclick="mf()"`. — nem035, Nov 06 '16 at 20:34
And it's not onlick, it's onclick. On lick is something else :) — Javier Rey, Nov 06 '16 at 20:36
`onlick` might be a nice addition for some future devices. We can only imagine ;-) — trincot, Nov 06 '16 at 20:36
I added a working example to my answer- please accept it if it helped — mancestr, Nov 06 '16 at 20:46
@ECoder- Under my answer score (between the up and down arrows, to the left of my answer), there should be a checkmark. Just click it, and that's it! Thanks! — mancestr, Nov 06 '16 at 21:06
Related: [When to use the `#` symbol to get a DOM element?](https://stackoverflow.com/q/15486154/4642212). — Sebastian Simon, Jul 06 '20 at 04:50

mancestr · Accepted Answer · 2016-11-06T20:41:47.603

5

You have two issues:

1): You're using

onlick="mf"

However, it should be:

onclick="mf();"

2): You used a # in your 'getElementByID'. This isn't jQuery- use

document.getElementById("sw")

Working Answer

"use strict";
 var s = 1;

  function mf() {
  setInterval(function() {
    document.getElementById("sw").innerText = s++;
   }, 1000);
 }

<div id="sw">0</div>
<input type="button" value="Start" name="start" onclick="mf();" />
<input type="button" value="Stop" name="stop" />

Your errors:

    document.getElementById("#sw").innerText = ++s;

should be

    document.getElementById("sw").innerText = s++;

Remove the #, and use s++, not ++s.

 <input type="button" value="Start" name="start" onlick="mf" />

That code has 2 errors: onlick and mf. Onlick isn't supported by all browsers yet (xD). Use onclick instead. Also, include the parameters, so mf()

edited Nov 06 '16 at 20:41

answered Nov 06 '16 at 20:37

mancestr

969
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6

`onclick` not `onlick` – nem035 Nov 06 '16 at 20:38
2

@nem035- thanks, I just copied what the OA used. I didn't check for that – mancestr Nov 06 '16 at 20:39
1

thank you now works very good. :) – E Coder Nov 06 '16 at 21:00

score 2 · Answer 2 · edited Nov 06 '16 at 22:52

2

First of all, you have a typo. You typed onlick instead of onclick. Second, document.getElementById takes a string that refers to the id of the element you are trying to get. However, it does not need a #.

document.getElementById("sw")

edited Nov 06 '16 at 22:52

mancestr

969
3
13
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answered Nov 06 '16 at 20:36

Gacci

1,388
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oh yes, thank you it solved. – E Coder Nov 06 '16 at 20:42

Why is this simple JavaScript stopwatch not working?

2 Answers2