Benchmark: Array reverse-and-pop vs shift, at a range of sizes

Array reverse-and-pop vs shift, at a range of sizes (version: 1)

Benchmarks the performance of two approaches for emptying an array from the front by sequentially removing each element. The methods are: A - first reversing the array with Array.reverse(), then using Array.pop() to remove each entry B - using Array.shift() to remove each entry

Comparing performance of: `100 - reverse and pop vs 100 - shift vs 1,000 - reverse and pop vs 1,000 - shift vs 10,000 - reverse and pop vs 10,000 - shift vs 100,00 - reverse and pop vs 100,000 - shift`

Created: one year ago by: Guest

Go to the latest result

Tests:

100 - reverse and pop
let arr = new Array(100) arr.reverse() while(arr.length > 0) { arr.pop() }
100 - shift
let arr = new Array(100) while(arr.length > 0) { arr.shift() }
1,000 - reverse and pop
let arr = new Array(1000) arr.reverse() while(arr.length > 0) { arr.pop() }
1,000 - shift
let arr = new Array(1000) while(arr.length > 0) { arr.shift() }
10,000 - reverse and pop
let arr = new Array(10000) arr.reverse() while(arr.length > 0) { arr.pop() }
10,000 - shift
let arr = new Array(10000) while(arr.length > 0) { arr.shift() }
100,00 - reverse and pop
let arr = new Array(100000) arr.reverse() while(arr.length > 0) { arr.pop() }
100,000 - shift
let arr = new Array(100000) while(arr.length > 0) { arr.shift() }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
100 - reverse and pop
100 - shift
1,000 - reverse and pop
1,000 - shift
10,000 - reverse and pop
10,000 - shift
100,00 - reverse and pop
100,000 - shift

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36

Browser/OS: Chrome 133 on Mac OS X 10.15.7

View result in a separate tab

100 - reverse and pop

3.6M/s

100 - shift

750K/s

1,000 - reverse and pop

332K/s

10,000 - reverse and pop

34K/s

1,000 - shift

19K/s

100,00 - reverse and pop

3K/s

10,000 - shift

2K/s

100,000 - shift

2/s

View exact numbers

Test name	Executions per second
✓ 100 - reverse and pop	3,568,219 Ops/sec
100 - shift	749,581 Ops/sec
1,000 - reverse and pop	331,909 Ops/sec
10,000 - reverse and pop	33,614 Ops/sec
1,000 - shift	18,645 Ops/sec
100,00 - reverse and pop	3,233 Ops/sec
10,000 - shift	1,736 Ops/sec
100,000 - shift	2 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON is designed to compare the performance of two different approaches for removing elements from an array in JavaScript:

1. **Using `Array.reverse()` followed by `Array.pop()`.**
2. **Using `Array.shift()` directly.**

### Comparison of Approaches

**Option A: Reverse and Pop (Array.reverse() + Array.pop())**
- **How it works:**
  - The array is first reversed using the `Array.reverse()` method, which rearranges the elements such that they can be removed from the end using `Array.pop()`.
- **Pros:**
  - Generally more efficient for larger arrays because `Array.pop()` removes elements from the end, which is an O(1) operation.
  - The initial reverse operation, although having a time complexity of O(n), is done once, and the subsequent removals can happen very quickly.
- **Cons:**
  - The `Array.reverse()` method incurs an overhead, particularly on very small arrays where the method is called but doesn't provide a performance advantage.
  - Reversing adds additional complexity and memory overhead as it creates a new arrangement of the original array.

**Option B: Shift (Array.shift())**
- **How it works:**
  - The `Array.shift()` method removes the first element from the array, shifting all subsequent elements down by one index.
- **Pros:**
  - Simple and straightforward; no need for additional operations such as reversing.
  - Directly modifies the original array without needing intermediate arrangements.
- **Cons:**
  - This method has a linear time complexity (O(n)) due to the need to shift all remaining elements to fill the gap after each removal, which can lead to poor performance on larger arrays.

### Considerations and Alternatives

- **Performance Results**: The benchmark results indicate that for smaller arrays (like 100 elements), using `Array.reverse()` and `Array.pop()` can be significantly faster than `Array.shift()`. However, as the size of the array increases, `Array.shift()` becomes increasingly inefficient due to shifting all the elements after each removal.
  
- **Browser Variability**: Performance can vary between different browser engines, as seen in the provided benchmarks, where results were collected from Chrome 133 on macOS. Developers should test across multiple environments to ensure consistent performance.

- **Alternatives**:
  - For situations where performance is critical and arrays are emptied frequently, consider using Collections such as `Deque` (Double-ended queue) from libraries like `collections.js` or implementing a custom linked list to avoid the performance pitfalls of array manipulations.
  - If data immutability is necessary, consider libraries like `Immutable.js`, which provide data structures that can be manipulated without mutating the original array.

Developers should choose the method that fits their requirements based on the size of the data and the expected frequency of operations, balancing performance, simplicity, and clarity of code.