Discussion on: Improve Your Algorithms with this Simple Equation

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Replies for: But calculating the array length has a cost of O(N). At the end there is no improvement un complexity

Array length isn't "calculated" it's a property of the Array, so to get the Array.length it is just O(1).

This is really interesting. However the only thing I find IS that it depends on the implementation.
Could you please send a source? I'm really interested on how this property gets calculated

aRtoo • Feb 7 '20

maybe joel is talking about javascript. Hes right its a property of an array. Thats how V8 implements it (sorry I cant find the link but Its in v8.dev). In other programming languages its still O(1) or constant time because it will do an arithmetic operation, example before c++14 (not sure) we do it in class was like totalNumberOfbytesInArray / numberOfBytesInInt. or maybe im wrong because it was 2008. lools

JavaScript Joel • Feb 7 '20

When an item is added to or removed from the array, the length property is updated. You can check this by running this code:

const array = [1, 2, 3];
array.length = 100;

console.log(array.length) //=> 100

length NEEDS to be a property, otherwise code like this would become exponential:

for (let i = 0; i < input.length; i++) { }

JavaScript Joel • Feb 7 '20

I think this Tweet is relevant to the discussion:

JavaScript Joel 🥑🍻

@joelnet

Object's are weird 😆

#JavaScript

18:57 PM - 07 Feb 2020

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