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JavaScript JavaScript Loops, Arrays and Objects Simplify Repetitive Tasks with Loops `do ... while` Loops

Juanpablo Villagomez
Juanpablo Villagomez
6,890 Points
Posted by Juanpablo Villagomez
Juanpablo Villagomez
6,890 Points

Question about the guess var

Is it necessary to declare the guess variable outside of the statement like that in the beginning? Wouldn't it be the same to declare the var guess prompt inside of the do while loop instead? the guess variable isn't being used anywhere else in the script aside from inside of the loop

1 Answer

Henrik Hansen
Henrik Hansen
23,176 Points
Henrik Hansen
Henrik Hansen
23,176 Points

Even if it is possible to declare the variable inside of the loop, you should not do that because you will be declaring that variable each iteration of the loop. Declaring a variable will allocate some memory for that var, and changing the value of that var will reuse the allocated memory instead of allocating new memory every time. It might not be a problem if the loop runs 10 times, but it will be a problem at 10000x. Even if unused vars will be garbage collected, we want to avoid this and try to keep a good memory management in our code. At least in Java the garbage collection is a very costly process, and I suspect it is in Javascript as well.

In other words, declaration of variables should only be done once, and then altered later on.

john larson
john larson
16,594 Points

Henrik, I've noticed you provide consistently good, straightforward answers.