Big O notation describes the performance or complexity of an algorithm. It shows the worstcase scenario and the execution time required or the storage space used by an algorithm too.
Hopefully, this article will help you understand the basic of Big O notation with JavaScript sample code.
🏈 O(1)
O(1)
shows the execution time(or space) of an algorithm is always same regardless of the size of the input data set.

🚌 O(N)
O(N)
illustrates an algorithm’s performance will grow linearly and in direct proportion to the size of the input data set. The example is as follows:

In Big O notation, we should always assume the upper limit where the algorithm will perform the maximum number of iterations. So, in that case, the worst case is return false
after finishing the loop.
🍣 O(N**2)
O(N**2)
(N squared) describes an algorithm whose performance is directly proportional to the square of the size of the input data set. This is common with algorithms that involve nested iterations. O Notation of deeper nested iteration will be O(N**3)
, O(N**4)
or etc.

🤔 O(2**N)
O(2**N)
represents an algorithm whose growth doubles with each addition to the input data set and it’s exponential.

🏀 O(log N)
Big O notation of Binary search like following example is O(log N)
.

O(log N)
algorithm like the binary search denotes produces a growth curve that peaks at the beginning and slowly flattens out as the size of the data sets increase. This makes algorithms extremely efficient when processing with large data sets.
🐝 Special Thanks
I wrote this article referencing A beginner’s guide to Big O notation  Rob Bell.
In addition, I could understand it with the following articles:
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