Do we need to “unset” variables in JavaScript?

Question

Do we need to unset variables in JavaScript, and why?

For example in PHP it's recommended to unset all temporary variables in all kind of loops to keep memory free and avoid variables duplicates.

But anyways according to php - what's the benefit of unsetting variables? question:

Is it true that unsetting variables doesn't actually decrease the memory consumption during runtime? -Yep.

So should we delete window.some_var;?

Or we should use some_var = null?

Or we should not unset variables to avoid additional CPU cycles?

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UPD: Related questions:

How to unset a Javascript variable?

How to remove a property from a javascript object

Answer 1

No, plus in some cases you can't delete variables in the global scope. Variables that are properly declared using the var keyword cannot be deleted (implied global variables can be deleted, on the other hand. Always use the var keyword to declare variables).

Also, javascript engines have this thing called garbage collector that automatically looks for variables that are no longer used or referenced somewhere when your code is 'running'. Once it finds one, it'll shove it off immediately into the Abyss (deletes the variable in the memory)