Needs Cleanup
This article needs cleanup to meet our writing standards:
- Spelling and punctuation
- Code clarity
- Avoid first person
Can you help? Click edit below!
Today i will be showing you how to save precious memory when using ajax requests.
Consider the following code
Event.observe(window,'load', function() { Event.observe('start','click',function() { i=0; interval=setInterval(function() { if(i<=60) { new Ajax.Updater('status','/periodical.php', { evalScripts:true, method : 'post', parameters : { value: i }, onComplete : function() { i++; }, insertion: Insertion.Bottom }); } else { clearInterval(interval); } },1000); }); });
and in the <body>
<input type="submit" value="Start test" id="start" /> <div id="status"> </div>
and on the server side :
echo("<pre>"); echo("<h1> ".$_POST['value']." </h1>"); echo("</pre>");
Okay we can see that this code calls an Ajax.Updater sending the value of the javascript variable ‘i` to the server - which the server echo’s back to the browser … nothing complicated there.. the code runs for 61 itterations once a second (so just over a minute) …
Okay so what i did was record my windows task manager output for firefox.exe when running this code …
With the code above the memory started at around 53,040k (give or take a byte) and ended on 55,112k (when the script had finished processing)
Okay now here is the code for the second unit test
Event.observe(window,'load', function() { Event.observe('start','click',function() { i=0; interval=setInterval(function() { if(i<=60) { var req=new Ajax.Updater('status','/periodical.php', { evalScripts:true, method : 'post', parameters : { value: i }, onComplete : function() { i++; }, insertion: Insertion.Bottom }); req=null; } else { clearInterval(interval); } },1000); }); });
Notice that not only assign the object to a variable but i also null the request out (req=null) when it has taken place… aside this the rest of the code is the same (html & php) as described earlier..
Here is the comparison
Code Example 1:-
Start Memory: 53,040k
End Memory: 55,112k
Total Script / page usage for the test: 2,072k
Code Example 2:-
Start Memory: 52,904k
End Memory: 54,116k
Total Script / page usage for the test: 1,212k
Saving 860k in the page - not sure what sort of percentage that is, but on large pages and ones that use preiodicals for chat scriptsit will save a hell of alot of memory
Hope you can put this to good use
/Alex
