setTimeout with or without anonymous function? What's the difference?

Question

I used this code (followed by an xmlhttprequest that fills the "tcap" textarea): ``` st=setTimeout(checkme(),4000) ``` where `checkme()` is: ``` function checkme() { if (typeof (st) != 'undefined') clearTimeout(st) if (document.getElementById("tcap").innerHTML.length > 0) { document.getElementById('waitmsg').style.display = 'none' } else { st = setTimeout(checkme(), 1000) } } ``` If I run it, it freezes Firefox 19 with no error message. But if I replace the first argument (both in code and in the checkme() function) with: ``` st=setTimeout(function(){checkme()},4000) ``` it works correctly. So my question is: what's the difference in calling the `checkme()` function with or without the anon function? Why in the first case it freezes Firefox? Thanks

Accepted Answer

You need to remove the parens in

```
st=setTimeout(checkme(),4000)
```

so instead:

```
st=setTimeout(checkme,4000)
```

otherwise, the function is invoked right away.

Since you have the same error inside the checkme function, it probably kills your browser due to unbounded recursion.

setTimeout with or without anonymous function? What's the difference?

Solution

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