Benchmark: Empty Array - MeasureThat.net

Script Preparation code:

var arr = [];
var size = 10000;
for (var i = 0; i < size; i++) {
 	arr.push(i);    
 }

Tests:

Length to zero
arr.length = 0;
Splice
arr.splice(0);
Pop
for (var j = arr.length; j > 0; j--) { arr.pop(); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Length to zero
Splice
Pop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.116 Safari/537.36

Browser/OS: Chrome 83 on Windows

View result in a separate tab

Test name	Executions per second
Length to zero	4010706.0 Ops/sec
Splice	5546541.5 Ops/sec
Pop	7172588.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into explaining the benchmark and its test cases.

**Benchmark Overview**

MeasureThat.net is a platform that allows users to create and run JavaScript microbenchmarks. A microbenchmark is a small, well-defined piece of code that measures the performance of a specific aspect of an engine or runtime environment. In this case, we have three test cases that compare different approaches for making an empty array.

**Test Cases**

The benchmark consists of three individual test cases:

1. **Length to zero**: This test case checks how fast it is to set the length of an array to 0.
2. **Splice**: This test case measures the time it takes to call `arr.splice(0)`.
3. **Pop**: This test case compares how fast it is to iterate through an array from its end using a for loop and pop elements.

**Library Used**

None, as these test cases do not rely on any external libraries.

**Special JavaScript Features or Syntax**

None mentioned in the provided benchmark definition. However, if we were to interpret "RawUAString" field, it might be related to User Agent string, but this is not a special JavaScript feature.

**Approach Comparison and Pros/Cons**

The three approaches are compared to determine which one is faster:

1. **Length to zero**: This approach uses the `arr.length = 0` assignment operator. The pros of this method are that it's concise and efficient, as it directly sets the length property without any intermediate operations. However, some engines might optimize away this operation, making it less performant.
2. **Splice**: Calling `arr.splice(0)` is a more traditional way to create an empty array. The pros of this method are that it's widely supported and can be useful in other scenarios where you need to remove elements from the start of an array. However, this approach has higher overhead due to the splicing operation.
3. **Pop**: This approach iterates through the array from its end using a for loop and pops elements. The pros of this method are that it's easy to understand and can be efficient if implemented correctly (e.g., by avoiding unnecessary iterations). However, this approach has higher overhead due to the repeated function calls and loop iterations.

**Considerations**

When interpreting these results, consider factors like:

* Browser support: Different browsers might optimize or behave differently for each test case.
* Engine implementation: The actual engine being used by the browser (e.g., V8 in Chrome) might have specific optimizations or behaviors that affect performance.
* Input size and distribution: The benchmark code generates a large array, but real-world scenarios might involve smaller or more evenly distributed data.

**Alternative Approaches**

If you want to explore alternative approaches for creating an empty array, consider:

1. `Array.prototype.fill()` with `fill(0)`: This method sets all elements of the array to 0 and can be faster than `arr.length = 0`.
2. Using a library like Lodash's `_.isEmpty()`: This function returns true if the array is empty and can be useful in certain scenarios.

Keep in mind that these alternative approaches might not be directly comparable to the original test cases, as they involve different assumptions about the input data and browser behavior.

Related benchmarks:

Empty Array (version: 0)

Compare standards methods for making an array empty.

Comparing performance of: Length to zero vs Splice vs Pop

Created: 4 years ago by: Guest

Jump to the latest result

Length to zero

Splice

Pop

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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