Benchmark: Split + Join vs replace regex

Script Preparation code:

var str = 'Abcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxyAbcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxy';

Tests:

replace regex
str.replace(/./g, "$&Z");
split+join
str.split('').join('Z') + 'Z';

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
replace regex
split+join

Fastest: N/A

Slowest: N/A

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/115.0.0.0 Safari/537.36

Browser/OS: Chrome 115 on Windows

View result in a separate tab

Test name	Executions per second
replace regex	128228.2 Ops/sec
split+join	184598.7 Ops/sec

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 Overview**

The provided benchmark compares three approaches to manipulate a string: replacing individual characters with a special character, joining an array of characters back into a string, and using regular expressions for replacement. The goal is to determine which approach is the fastest.

**Script Preparation Code**

The script preparation code provides the input string `str` that will be used in both test cases:
```javascript
var str = 'Abcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxyAbcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxy';
```
This string is repeated 20 times to create a large dataset, making the benchmark more representative of real-world performance.

**Test Cases**

There are two test cases:

1. **replace regex**: Replaces each character with a special character `$&Z`.
```javascript
str.replace(/./g, "$&Z");
```
2. **split+join**: Splits the string into an array of characters using `split('')`, joins them back into a string using `join('')`, and appends a trailing 'Z' to each character.
```javascript
str.split('').join('Z') + 'Z';
```
**Options Compared**

The two test cases use different approaches to manipulate the input string:

* **replace regex**: Uses regular expressions to replace individual characters with a special character. This approach is typically faster than other methods because it leverages the browser's optimized string replacement engine.
* **split+join**: Splits and joins the string using array operations, which can be slower due to the overhead of creating an array and iterating over its elements.

**Pros and Cons**

* **replace regex**:
	+ Pros: Often faster than other methods because it uses the browser's optimized string replacement engine.
	+ Cons: Requires a regular expression engine, which may not always execute correctly or efficiently.
* **split+join**:
	+ Pros: May be more readable and easier to understand for some developers.
	+ Cons: Can be slower due to array creation and iteration overhead.

**Library Used**

There is no specific library used in this benchmark. The `str.replace()` method uses the browser's built-in string replacement engine, while the `split()` and `join()` methods use the DOMStringManipulation API.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntaxes used in this benchmark.

**Other Alternatives**

If you were to replace these test cases with alternative approaches, some options might include:

* **using a library like Lodash**: Implementing a custom string manipulation function using a library like Lodash could potentially be faster than the browser's built-in methods.
* **using WebAssembly**: Compiling the benchmark code to WebAssembly and running it in a WebAssembly runtime could provide improved performance due to the optimized execution environment.
* **using a different string replacement approach**: Implementing a custom string replacement algorithm using bitwise operations or other techniques could potentially be faster than the `replace()` method.

Keep in mind that these alternatives may not always result in significant performance improvements, and the choice of approach depends on the specific requirements and constraints of your project.

Related benchmarks:

Split + Join vs replace regex (version: 0)

Comparing performance of: replace regex vs split+join

Created: one year ago by: Guest

Jump to the latest result

replace regex

split+join

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):