Benchmark: JS Slice vs. Pop vs index for last element

Script Preparation code:

var x = [1,2,3]

Tests:

slice
x.slice(-1)[0]
pop
x.pop()
index
x[x.length-1]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
pop
index

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
slice	53050548.0 Ops/sec
pop	194209040.0 Ops/sec
index	1419647872.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases.

**Benchmark Definition:**
The JSON object represents a JavaScript microbenchmark named "JS Slice vs. Pop vs index for last element". This benchmark is designed to compare the performance of three different ways to access the last element of an array:

1. `x.slice(-1)[0]`
2. `x.pop()`
3. `x[x.length-1]`

**Options Compared:**
These three options are compared to determine which one is the fastest.

**Pros and Cons of each approach:**

1. **`x.slice(-1)[0]`**:
	* Pros: Returns the last element without modifying the original array, which can be more predictable in certain situations.
	* Cons: Creates a new array object, which can be expensive in terms of memory allocation and copying.
2. **`x.pop()`**:
	* Pros: Modifies the original array by removing the last element, which can reduce memory usage for large arrays.
	* Cons: Removes the last element from the array, which may not be desirable if the array needs to be preserved.
3. **`x[x.length-1]`**:
	* Pros: Directly accesses the last element of the original array without creating a new object or modifying it.
	* Cons: May cause a stack overflow error for very large arrays (arrays with more than 2^53 - 1 elements), as it relies on integer arithmetic to compute the index.

**Library Usage:**
None of the test cases use any libraries, which means the results are solely dependent on JavaScript's built-in functionality.

**Special JS Features/Syntax:**
There is no special JavaScript feature or syntax used in these test cases. The focus is purely on comparing the performance of different array access methods.

**Other Alternatives:**
If you wanted to write this benchmark yourself, you could consider using a framework like Benchmark.js (which is actually where MeasureThat.net got its name from!) or Node.js's built-in `benchmark` module to create similar tests. You could also use libraries like `micro-benchmark` or `fastdom` to simplify the process.

In terms of implementing this benchmark, you would:

1. Create an array of a suitable size (e.g., 1000 elements).
2. Define a function that accesses the last element of the array using each of the three methods (`slice`, `pop`, and direct indexing).
3. Run each test case multiple times to account for any variability in execution time.
4. Use a framework like Benchmark.js or Node.js's built-in `benchmark` module to create a benchmark that can be run against different browsers and devices.

Keep in mind that this is just one way to implement a benchmark, and the actual implementation will depend on your specific needs and requirements.

Related benchmarks:

JS Slice vs. Pop vs index for last element (version: 0)

Comparing performance of: slice vs pop vs index

Created: 2 years ago by: Guest

Jump to the latest result

slice

pop

index

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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