Benchmark: Array pop vs shift

Script Preparation code:

var arr1 = [0,1,2,3,4,5,6,7,8,9];
var arr2 = [];

function getLastPop(arr) {
  return arr.pop();
}

function getLastAt(arr) {
  return arr.shift();
}

Tests:

pop
getLastPop(arr1); getLastPop(arr1); getLastPop(arr2);
at
getLastAt(arr1); getLastAt(arr1); getLastAt(arr2);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
pop
at

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36

Browser/OS: Chrome 121 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
pop	5623152.0 Ops/sec
at	5489785.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's dive into the benchmark definition and test cases.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmark that compares two approaches for removing an element from an array: `pop-push` and `shift`. The script preparation code defines two functions:

1. `getLastPop(arr)`: This function uses the `pop()` method to remove and return the last element of the input array `arr`.
2. `getLastAt(arr)`: This function uses the `shift()` method to remove and return the first element of the input array `arr`.

**Options Compared**

The benchmark compares two options:

1. **Pop-Push Method**: The `pop()` method is used to remove an element from the end of the array, and a new element is added to the end using the `push()` method.
2. **Shift Method**: The `shift()` method is used to remove and return the first element of the array.

**Pros and Cons**

Here are some pros and cons of each approach:

1. **Pop-Push Method**:
	* Pros: This method can be more efficient for arrays with a large number of elements at the end, as it only requires one operation to remove an element.
	* Cons: This method creates a new array, which can lead to memory overhead and potentially slow down the benchmark if the input array is large.
2. **Shift Method**:
	* Pros: This method does not create a new array and instead modifies the original array in place, which can be more memory-efficient.
	* Cons: The `shift()` method returns only one element, whereas `pop()` returns both the removed element and the new length of the array.

**Library and Special JS Features**

Neither of these approaches uses any external libraries. There are no special JavaScript features or syntax mentioned in this benchmark.

**Other Alternatives**

If you want to explore other approaches for removing an element from an array, consider the following:

1. **Slicing**: You can use slicing (`arr.slice(0, -1)`) to remove the last element of an array.
2. **Splice**: The `splice()` method can be used to remove elements at a specific index or position in an array.
3. **Array destructuring**: In modern JavaScript, you can use array destructuring to extract individual elements from an array.

The choice of approach depends on the specific requirements and constraints of your use case. If you need to optimize for memory efficiency, the `shift()` method might be a better choice. However, if you prioritize simplicity and don't mind creating a new array, the pop-push method could be more suitable.

Related benchmarks:

Array pop vs shift (version: 0)

Comparing pop-push method vs shift for array element

Comparing performance of: pop vs at

Created: 2 years ago by: Guest

Jump to the latest result

pop

at

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):