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In the following code:
for (var i = 0; i < object.length; i++){
....
}
does the operation object.length get evaluated every time in the iteration?
It would make most sense that the language will evaluate this once and save the result. However, I was reading some code where someone evaluated the operation before the loop started and stored it in a variable that was used in the end-condition.
Do different languages handle this differently? Any specific info for Javascript?
It obviously depends on the language. For JavaScript, the spec (ECMAScript §12.6.3) requires it always be evaluated each time. As an optimization, a specific JavaScript runtime could skip one or more of the length calls, if it could prove that the result would not change.