You may not know that most of the js websites you browse will cause memory leaks. Sounds a bit exaggerated but it’s true, would I lie to you?
Leak Monitor
This is a convenient FireFox extension. When you leave the page, it will point to the JavsScript object. If a leak occurs, a window will pop up to show the details, and it can tell you which object or function caused the leak.
When leaving http://script.aculo.us/
This is probably my most common leak prototype.js, line 74:3
The Dojo Mail example page
A serious leak, two windows popped up at once (pay attention to the scroll bar!).
Word Press
This is even more outrageous. Every time I finish writing Word press, it will appear!
Visit general sites and you will find that most sites will have this kind of problem. Indeed, it can be a bit of a shock if some websites have not gone through such testing - a few minor changes could have ensured that this problem would not occur.
Although this website (Jack'sBlog, examples) is all JavaScript, you don't have to worry about any risk of leakage.
Here are three simple steps:
1. When you are done, set your XMLHttpRequest onreadystatechange handlers to null,
I use YAHOO.util.Connect for XHR linking because it uses polling mechanism instead of readstate, so I don't have to set null manually. I recommend that you, where possible, use YAHOO.util.Connect (or YAHOO.ext.UpdateManager built on top of it).
2. Clear all DOM event handlers objects in the unload event, if they have a chance to reference (Refence).
If you can ask Library to do it, don’t do it your own way! For the event mechanism, I use YAHOO.util.Event to handle it. Other libraries (prototype, dojo, etc) also have their own corresponding mechanisms to handle it. --Though I don't know how efficiently they go there. If you look at the screenshot above carefully, you will find that the leaked code above will be associated with these libraries (use facts to prove the source of the accident, Frank's note)
3. In addition to some basic types of data primitive value (String , Number), never put anything else in the DOM expando or property. Of course, there is an exception if you can ensure that you clear it in time.
This is the most important golden rule. You may find it convenient to put something in the DOM expando, and then use $() to get it, but never do this. Really, I know what you are thinking. Now I have admitted to being wired and paranoid. Yes, JS objects are put into DOM expando on many occasions, and nothing happens, but there are many. . . . This situation is not easy to detect! (For example: closure closure). So to avoid any possible occurrence, I will only follow this rule.
Summary
It’s not too difficult to solve this problem. It requires no skills or experience. As long as you pay attention to the above points, a novice novice will also know how to avoid leaks.
Please please take some time and effort from some of the big sites (including the new Yahoo Mail!?!?) to allow me (or others) to browse your pages without suffering memory leaks.
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