Benchmark: Pop vs length -1

Script Preparation code:

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

Tests:

pop
array.pop();
length - 1
array[array.length - 1];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
pop
length - 1

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Definition**

The provided benchmark definition json represents a simple test that compares two approaches to access the last element of an array: `array.pop()` and `array[array.length - 1]`.

**Options Compared**

There are two options being compared:

1. **`array.pop()`**: This method removes and returns the last element from the array, modifying the original array.
2. **`array[array.length - 1]`**: This approach accesses the last element of the array without modifying it.

**Pros and Cons of Each Approach**

**`array.pop()`**:

Pros:

* Can be faster for accessing arrays that are frequently resized or updated, as it avoids the need to calculate the index.
* May be more suitable for use cases where the last element is not the only one accessed.

Cons:

* Modifies the original array, which can lead to unexpected behavior in some contexts.
* May incur additional overhead due to the removal and updating of the array's internal state.

**`array[array.length - 1]`**:

Pros:

* Does not modify the original array, making it safer for use cases where the array is not meant to be changed.
* Can be more efficient for accessing arrays that are not frequently updated or resized.

Cons:

* May incur additional overhead due to the calculation of the index.
* Can lead to slower performance when dealing with large arrays.

**Library and Special JS Features**

In this benchmark, there are no specific libraries used. However, it's worth noting that `array.pop()` is a built-in JavaScript method, while `array[array.length - 1]` is also a built-in expression that accesses the last element of an array without modifying it.

No special JavaScript features or syntax are used in this benchmark.

**Other Considerations**

When writing microbenchmarks like this one, it's essential to consider factors such as:

* **Data size**: The size of the input data can significantly impact performance. This benchmark uses a fixed-size array with 100,000 elements.
* **Array resizing**: If the array is resized frequently during execution, `array.pop()` may incur additional overhead due to internal array state updates.
* **Platform and browser differences**: As shown in the latest benchmark result, there are differences in performance across different browsers and platforms. This highlights the importance of considering platform-specific factors when writing benchmarks.

**Alternative Benchmarks**

Other alternatives for comparing these two approaches might include:

* Using a larger or smaller dataset to test the scalability of both methods.
* Adding more elements to the array before accessing the last element, simulating real-world usage patterns.
* Introducing additional operations within the array, such as sorting or filtering, to further stress the performance of both methods.

By considering these alternative approaches, you can gain a deeper understanding of how different scenarios affect the performance of `array.pop()` and `array[array.length - 1]`.

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36

Browser/OS: Chrome 112 on Windows

View result in a separate tab

Test name	Executions per second
pop	12192195.0 Ops/sec
length - 1	4165738.8 Ops/sec

Related benchmarks:

Pop vs length -1 (version: 0)

Comparing performance of: pop vs length - 1

Created: one year ago by: Guest

Jump to the latest result

pop

length - 1

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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