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How to destroy things correctly?


clark
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In actionscript you would get an error if you tried to call a method of an object which did not exist and I am guessing JS is the same.
 

function destroy(): void{     this._apple.destroy()   //error, you cannot call destroy() because this._apple is null or undefined}

So what I end up doing was this which worked for a decade:
 

function destroy(): void{     if (this._apple != null)     {          this._apple.removeEventsBlah...          this._apple.destroy();          this._apple = null;     }     }

But this feels primitive. When you have like 12 class members, and you got to check if they are null.

Apart from that, I read this is not accurate for JS? I should use typeof?

So if typeof variable === "undefined" 

Basically, how do you correctly destroy objects? Is it merely enough in JS just to null it....  this._apple = null.  I am not sure how stuff works without a virtual machine doing garbage collection where it is important to remove all listeners/references while I am struggling to figure out what is null in relation to undefined. 

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Yes it is enough just to set it to null if you want it empty. Do not set it to undefined.

 

Undefined is, of what I've known:

1. What is thrown when your variable is not initialized (var a;)

2. Calling an out of bounds array elements (a[5] when array length is actually 4)

3. Getting a value where a function doesn't return a value.

4. Passing parameter when it is not passed any value (function myMethod(a, b ) {} --> usage: myMethod(5), then b is undefined).

 

It is preferable, even if possible, not to use any uninitialized variables for any use (including typeof), in this case "undefined", until you assign it with value, which is at least a null value.

 

Regarding to your garbage collection issue, when the object is no longer used/have no reference whatsoever, it will be taken care by JavaScript, even if you don't set it to null. For example, you have a Human object that has a Hand object. When you set a human object variable to null, then Hand object will be garbage collected without you needing to destroy it in Human's destructor like C++, nor you need to manually call "human.cleanUp()" to set that hand object to null.

This is just the same as ActionScript, C#, and Java.

 

The only way to manage this automatic garbage collection is how you manage your variables around the application without losing them, like using object pooling.

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