javascript - Are these valid Loop optimizations? -

if following, considered un-optimal (performance wise)?

// optimal? foreach (var fruit in basket.fruits()) {   // .... }  // this? (var = 0; < basket.fruits().length; ++i) {   // .... }  // alternate way. var fruits = basket.fruits(); foreach (var fruit in fruits)  {   // .... } 

im looking answers applicable .net javascript.

thank you.

both equally performant. basket.fruits() returns object , javascript create iterator object.

another solution use

object.keys(basket.fruits()).foreach(function(fruit) {   // ... }); 

either way, don't focus on kind of optimization. javascript fast , there many automatic optimizations. should focusing on making code legible possible. after it's done, if find slow part, focus on optimizing part.

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according edit, store array's length in variable in initialization expression of loop. predicate expression can compare i<len instead of computing array length each iteration.

for (var i=0; len=basket.fruits().length; i<len; i++) ...