JavaScript 개체, 배열 및 해당 메서드의 Big O 시간 복잡성

An object is a data container, where the collection of properties save in key-value pair format between the curly braces {}.

Generally, the key-value pair is known as the property name and property value, where the property name should be unique, and it stays on the left side before colon ":" and property values on the right side after the colon.

To separate individual property, we use a comma.

Example:

var obj = {name:"Himanshu", jobProfile:"SDE"}

Note: If the same property name with a different value is created again in the object, JavaScript considers only new property.

We should use it when we don't need to save data in order, and at the same time required to get fast access, fast insertion, and removal.

1. Insertion Operation: Happens in O(1)
2. Removal Operation: Happens in O(1)
3. Searching Operation: Happens in O(N)
4. Access Operation: Happens in O(1)
5. Object.keys Method: Happens in O(N)
6. Object.values Method: Happens in O(N)
7. Object.entries Method: Happens in O(N)
8. hasOwnProperty Method: Happens in O(N)

var arr = [1,2,3,4,null,() => 5]

An array is a data container that follows the linear data structure, which means all elements store in a sequential manner. The great thing about an Array in javascript is:

1. It is dynamic, which means we can store almost all types of value in an array.
2. As it is a dynamic array, we don't need to specify the length of an Array in advance like other languages.

We should use it when we need to save data in order, and at the same time required to get fast access, fast insertion, and removal.

Note:Fast Insertion and removal depend on where you are adding and removing from

1. Insertion at the end of an Array: O(1)
2. Removal at the end of an Array: O(1)
3. Insertion at the beginning & mid of a non-empty Array: O(1)
4. Removal of item from the start & mid of a non-empty Array: O(1)
5. Searching if an Array unsorted: O(N)
6. Searching if an Array sorted: Depends on the algorithm
7. Access: O(1)
8. push (inserting element at the end of an array): O(1)
9. pop (deleting an element from the end of an array): O(1)
10. Shift(opposite to push, and it shifts next elements to next index position): O(N)
11. unshift (opposite to pop, and it shifts elements to the previous index position): O(N)
12. concat: O(N)
13. slice: O(N)
14. splice: O(N)
15. sort: depends
16. forEach, map, filter, reduce: O(N)