Memory Management In Javascript

by HSG on Nov 11, 2012 in JavaScript Tutorial

Memory management is always a priority in pretty much any programming language you would want to use. In the lower level languages such as C, there are a number of functions which help you manage the memory your application uses, but they are not the easiest to use. Some of the more modern programming languages such as Python, Ruby, Perl, and of course the subject of this article, Javascript all have a built in feature called garbage collection.

 

Garbage collection essentially means that the languages compiler will automatically free the memory being occupied by unused variables and objects, but there is no telling when this could occur. It is purely down to the compiler to decide when the garbage collection process should be initiated.

 

When it comes to programming with Javascript, the thought that you do not have to deal with how much memory is being used by a particular object or variable, can make life a whole lot easier. But that does not mean you should not keep it in mind when you are working on your application.

 

Take a look at the following code snippet:

 

     var a = 123;

     var b = "azerty";

 

Looking closely at the above code you would think that all we are doing is creating two variables and assigning a value to each, but under the hood Javascript also automatically allocates memory for those two variables, and it does the exact same thing when you create an array or an object.

 

The biggest problem faced by any langauge is the simple fact that there is no way to tell when a certain piece of memory is no longer needed. For example, if you have initialized an array containing some phone numbers which only need to be displayed once, then it seems a waste of memory to have that array sit there and do nothing while the space it is occuping could be used by other parts of the application.

 

What you have to keep in mind is that computer you develop your applications on may be powerful and loaded with lots of memory, but the end users of your software may not have the same computing power at their disposal. This becomes more important with web applications which run through the users browser, which in itself could be using a fair slice of the computers memory depending on what it is doing.

 

As mentioned near the beginning of this article, there is no way to tell when the garbage collection process will kick in and free the unused memory, but you as the programmer can help things along by being a little more dilligent with your variables and objects creation. As an example, if you create an application using Javascript and find that you have created several variables which the software actually ends up not using, then remove them.

 

Likewise, if you only use a variable or object once in your application and find you no longer need to use them, then set its value to null so it will use less memory. Always keep memory management in mind no matter what language you end up working with.

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