[jQuery] Preventing closure memory leaks.
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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’m sure this will be a d’oh for a number of
people, and something I should have known a long time ago, but I figured I’d
share it just in case it helps someone else.<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I ran into a memory leak problem a few months back due to an
incorrect use of closures in my code. I managed to fix it, but have very been
nervous about using them ever since, even to the point of writing complex
workarounds rather than just using a closure when it would have been
appropriate.<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Anyway, (and here is the d’oh part), all I had to do
was null out the variables used in the closure and the crappy Internet Explorer
garbage collector would be able to clean it up, preventing memory leaks.<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Example code snippet:<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>var el = $(this);<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>setTimeout(function()<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>{<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> el.hide();<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> el = null;<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>},1000);<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I did some tests with sIEve with different types of
closures, and so long as I nulled out the context variables, I didn’t get
any memory leaks.<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Of course, it is still best practice to only use closures
when it is appropriate, and NEVER by mistake, but so long as you null out the
variable that CAUSED the closure, it seems to handle the problem IE has with
garbage collection.<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Thoughts? Feedback?<o:p></o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>JK</span></font><o:p></o:p>
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