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Now one word about memory consumption and memory usage.

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If every function logs in all surrounding variables, doesn't that lead to a pretty bad effect in our

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memory because in big applications where we have many variables, a function might log in a lot of variables

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which it never uses.

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So Javascript doesn't get rid of these variables because a function closed over them but the function

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might never get called or even if it gets called, it might not be interested in all variables,

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so isn't that a memory issue?

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In theory, it would be but of course Javascript engines are pretty smart or the people who are working

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on them are pretty smart and therefore, modern Javascript engines optimize this.

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They basically track variable usage you could say and if a variable obviously isn't getting used

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by anything, not by any functions and nowhere else, then they will get rid of it and they will do so of

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course in a safe way so that they don't accidentally crash your program because you need to use that

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function at some point of time,

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they're really smart about that and they optimize this whole behavior so that you don't manually have

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to reset all variables that you don't need, Javascript engines will do that for you in a smart way.