While Loops vs. For Loops in JavaScript? [closed]

Question

What are the benefits of using a while loop over a for loop? When I'm iterating through arrays, I always use a for loop so I wondered if I'm missing something here.

I've never had a situation where a for loop doesn't do the job, but I'm worried that I may be picking up bad habits here. My usage of loops has been with regards to elements on web pages, stuff in animations, etc..

Answer 1

These are the reasons I would choose one over the other:

For-loop Syntax:

for( int i = 0; i > 10; i++) {     //Some code here } 

I would use a for loop for the reason that I may KNOW the NUMBER OF ITERATIONS I need to do and I have an INCREMENTING variable which can be handy sometimes.

While-loop Syntax:

while(!done) {     //Some code goes here } 

I would use this loop when I am NOT SURE how many ITERATIONS I might need to carry out. Examples: Waiting for user to input correct input values and keep looping until he/she inputs the proper value.

Do-While loop Syntax:

do {     //Some code here } while(!done); 

This loop is almost the same as a while-loop but I would prefer this when I need something done ATLEAST ONCE before I start verifying whatever it is that would make me wanna loop and do that code again. Example: ask a user for an input for the first time and then validate it. If wrong input given then loop back and ask for input again

Answer 2

Functionally, one can substitute the other in all conditions. Is one better than the other? Not in javascript (which you have tagged) as its not a compiled language.

But in languages like C++, a for loop usually gives the compiler a static count to loop which the compiler can use to optimize the binary. So it should run faster (on very large loop counts).

That should not be a worry in today's age where you won't even notice the performance increase on a loop running for 10000 iterations on a 2.5 ghz quad core CPU.

However, personally, aesthetics matter to me (and it should to you if you are serious about the art of coding) a lot. For example when you are dealing with an external condition (the variable you are checking is defined outside the loop), go with a while loop. Its just semantically so much beautiful. Also while loop should be the de-facto choice for an infinite loop (I don't see a reason why you would have an infinite loop in javascript, though).

In short, follow the syntax. Are you just checking a condition? Go with a while loop. Are you initializing and incrementing/decrementing something with in the context of a loop along with checking a condition? Only then go with the for loop.