Benchmark: pop() vs shift()

Script Preparation code:

var array = [];

for(var i = 0; i < 100000; i++){array.push(Math.random());}

Tests:

pop
while (array.length > 0) { array.pop(); }
shift
while (array.length > 0) { array.shift(); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
pop
shift

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:148.0) Gecko/20100101 Firefox/148.0

Browser/OS: Firefox 148 on Linux

View result in a separate tab

Test name	Executions per second
pop	638205312.0 Ops/sec
shift	1591614720.0 Ops/sec

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

LLMs can make mistakes. Check important info.

The provided JSON benchmark focuses on comparing the performance of two array manipulation methods in JavaScript: `pop()` and `shift()`. Here’s a detailed explanation of what is being tested, the options compared, and their respective pros and cons.

### Benchmark Overview
- **Benchmark Name**: `pop() vs shift()`
- **Setup**: The benchmark initializes an empty array and fills it with 100,000 random numbers using `Math.random()`.

### Test Cases
1. **pop**:
   - **Function**: `array.pop()`
   - **Behavior**: The `pop()` method removes the last element from an array and returns that element. It modifies the length of the array.
   - **Benchmark Definition**: It uses a `while` loop to continually remove elements until the array is empty: `while (array.length > 0) { array.pop(); }`.
   
2. **shift**:
   - **Function**: `array.shift()`
   - **Behavior**: The `shift()` method removes the first element from an array and returns that element. Like `pop()`, it modifies the length of the array.
   - **Benchmark Definition**: This also uses a `while` loop to remove elements until the array is empty: `while (array.length > 0) { array.shift(); }`.

### Performance Metrics
- **Executions per Second**: 
  - `pop()`: Approximately 69,014,224 operations per second.
  - `shift()`: Approximately 68,533,288 operations per second.

From the benchmark results, we observe that `pop()` performs slightly better than `shift()`.

### Pros and Cons of Each Method

#### pop() Method
- **Pros**:
  - Generally faster than `shift()` since it operates on the end of the array, where no re-indexing of other elements is needed.
  - Commonly used in stack data structure implementations.

- **Cons**:
  - Only useful if you need to remove elements from the end. It doesn't fit use cases where elements need to be removed from the beginning.

#### shift() Method
- **Pros**:
  - Useful for implementing queues where you often need to remove the first element in an orderly fashion.
  - Provides an easy and straightforward way to manipulate arrays.

- **Cons**:
  - Slower than `pop()` because it requires re-indexing all the other elements in the array after removing the first element. This can lead to performance bottlenecks, especially for large arrays.

### Other Considerations
- **Alternatives**: In scenarios where frequent removals from the start of the array are required, using data structures optimized for such operations, like linked lists, may be a better alternative. While JavaScript does not natively support linked lists, developers can implement them to gain better performance for specific use cases.
- **Library Implications**: The benchmark does not utilize an external library; it relies solely on built-in JavaScript methods. This ensures that the results are consistent across different JavaScript engines since these methods are standard in the ECMAScript specification.
  
In summary, this benchmark evaluates a fundamental aspect of array manipulation in JavaScript. It highlights the differences in performance and use cases between the `pop()` and `shift()` methods, informing developers about when to use each method based on their performance characteristics and application needs.

Related benchmarks:

pop() vs shift() (version: 1)

Comparing performance of: pop vs shift

Created: one year ago by: Guest

Jump to the latest result

pop

shift

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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