The Big O of Objects and Array

https://cs.slides.com/colt_steele/built-in-data-structures-25

 

When to use objects, don’t need order

Need fast access O(1) / insertion O(1) / removal O(1)  in constant time.

Searching O(N) in linear time

 

Big O of Object Methods

Object.key O(N)

Object.values O(N)

Object.entries O(N)

hasOwnProperty O(1)

 

Big O of Array

Searching O(N)

Access O(1)

Insertion depends on where to put. It has to re-index every single element in the array

Same goes to removal.

 

It is good to beware that it is not as efficient as adding in removing at the end.

so push and pop always faster than shift and unshift.

 

Built in Array Method

 

Big O of Array Operations

Push O(1)

Pop O(1)

Shift O(N)

Unshift O(N)

Concat O(N)

Slice O(N)

Splice O(N)

Sort O(N* logN)

forEach/mat/filter/reduce/etc… O(N)