Benchmark: Split join vs replace

Script Preparation code:

var example = 'AgreementChangeId'

Tests:

split + join
var result = example.split(/(?=[A-Z])/).join(' ');
replace
var result = example.replace(/([A-Z]+)/g, ' $1')

Historical Performance Data aggregated from 51 community runs

Desktop Results:

Chrome 42 runs

replace

3.2M/s

split + join

3.0M/s

View exact numbers

✓ replace: 3,225,746 ops/sec
• split + join: 2,992,290 ops/sec

Firefox 9 runs

split + join

2.9M/s

replace

2.5M/s

Fastest: split + join (1.2x faster)

View exact numbers

✓ split + join: 2,936,964 ops/sec
• replace: 2,521,992 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
split + join
replace

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 6 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:147.0) Gecko/20100101 Firefox/147.0

Browser/OS: Firefox 147 on Windows

View result in a separate tab

split + join

2.1M/s

replace

1.6M/s

View exact numbers

Test name	Executions per second
✓ split + join	2,078,041 Ops/sec
replace	1,609,118 Ops/sec

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):

LLMs can make mistakes. Check important info.

Let's dive into what this benchmark is testing.

**What is being tested?**

The benchmark is comparing the performance of two different approaches to split and join a string in JavaScript:

1. **Splitting with regular expression and joining**: This approach uses the `split()` method with a regular expression (`(?=[A-Z])/`) to split the input string into an array, and then uses the `join()` method to concatenate the array elements back into a string.
2. **Replacing with regular expression**: This approach uses the `replace()` method with a regular expression (`([A-Z]+)/g`)) to replace each uppercase letter in the input string with itself followed by a space.

**What are the pros and cons of these approaches?**

Both approaches have their own trade-offs:

* **Split + Join**:
	+ Pros: Can be more flexible if you need to split on multiple patterns or adjust the split points.
	+ Cons: Requires creating an array, which can lead to increased memory usage. The `join()` method also introduces additional overhead.
* **Replace**:
	+ Pros: Directly achieves the desired outcome with a single operation, potentially reducing memory allocation and garbage collection.
	+ Cons: Limited flexibility if you need to split on multiple patterns or adjust the replacement points.

**Other considerations**

When choosing between these approaches, consider the following factors:

1. **Input size**: If working with very large strings, splitting and joining might lead to significant memory usage and slower performance due to array creation.
2. **Pattern complexity**: If you need to split on multiple patterns or adjust the split points, the `split()` method with a regular expression is more suitable.

**What library or feature is used?**

None of the provided test cases use any external libraries beyond JavaScript's built-in functionality.

**What are other alternatives?**

Some alternative approaches include:

1. **Using a loop**: You can manually iterate over the input string and insert spaces at the desired positions.
2. **Custom implementation**: Depending on the specific requirements, you might be able to implement your own custom solution using bitwise operations or other low-level techniques.
3. **Higher-order functions**: If working with functional programming concepts, you could use higher-order functions like `map()` and `reduce()` to transform the input string.

Keep in mind that these alternatives may have their own performance implications and trade-offs depending on the specific use case.

Split join vs replace (version: 0)

Comparing performance of: `split + join vs replace`

Created: 5 years ago by: Guest

Go to the latest result

split + join

replace

Historical Performance Data aggregated from 51 community runs

Desktop Results:

Chrome 42 runs

Firefox 9 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):

Split join vs replace (version: 0)

Comparing performance of: split + join vs replace

Created: 5 years ago by: Guest

Go to the latest result

split + join

replace

Historical Performance Data aggregated from 51 community runs

Desktop Results:

Chrome 42 runs

Firefox 9 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):

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Comparing performance of: `split + join vs replace`