Benchmark: replaceAll vs regex replace with and without repetition

Tests:

replace regex with repetition
"this is it".replace(/ +/g, "");
replaceAll
"this is it".replaceAll(" ", "");
replace regex without repetition
"this is it".replace(/ /g, "");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
replace regex with repetition
replaceAll
replace regex without repetition

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36

Browser/OS: Chrome 121 on Linux

View result in a separate tab

replace regex with repetition

6.3M/s

replace regex without repetition

6.2M/s

replaceAll

5.8M/s

View exact numbers

Test name	Executions per second
✓ replace regex with repetition	6,316,165 Ops/sec
replace regex without repetition	6,177,136 Ops/sec
replaceAll	5,760,026 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 benchmark and its components.

**Benchmark Overview**

The benchmark is designed to compare the performance of three JavaScript methods for replacing strings: `replace()`, `replaceAll()`, and regular expressions (`/regex/g`).

**Methods being compared**

1. **`replace()`**: This method uses a string replacement approach, where it replaces all occurrences of a specified substring with another substring.
2. **Regular Expression (`/regex/g`) without repetition**: This method uses a regular expression to match the pattern and replace it with a new string. The `/g` flag at the end of the regex indicates "global" mode, which means the replacement will be applied to all matches in the string, not just the first one.
3. **Regular Expression (`/regex/g`) with repetition**: This method is identical to the previous one, but with an extra parameter that repeats the new substring for each match.

**Pros and Cons of each approach**

1. **`replace()`**:
	* Pros: Simple and easy to implement.
	* Cons: Can be slow if the string is large or if the replacement pattern is complex.
2. **Regular Expression (`/regex/g`) without repetition**:
	* Pros: Fast and efficient, especially for large strings or complex patterns.
	* Cons: Requires more effort to set up the regex pattern correctly.
3. **Regular Expression (`/regex/g`) with repetition**:
	* Pros: Similar benefits as the previous method, but with the added flexibility of repeated replacements.
	* Cons: May be slower than the `replace()` method due to the additional overhead of repeating the new substring.

**Library usage**

None of the methods explicitly use a library in this benchmark. However, it's worth noting that some JavaScript engines (like V8) provide optimized implementations for certain string replacement methods.

**Special JS features or syntax**

* None mentioned.

**Other alternatives**

Some alternative approaches to these three methods include:

1. **`String.prototype.replace()` with a callback function**: This method allows you to specify a custom function to be executed for each match, which can be useful in more complex scenarios.
2. **`String.prototype.replaceAll()`**: Some modern JavaScript engines (like V8) provide an `replaceAll()` method that is similar to the `replace()` method but uses a different internal implementation.

**Benchmark setup**

The benchmark is likely set up using MeasureThat.net's interface, which allows users to create and run custom benchmarks. The script preparation code for each test case would involve importing any necessary libraries (e.g., jQuery) and setting up the string replacement tests.

replaceAll vs regex replace with and without repetition (version: 0) Benchmark.js

Comparing performance of: `replace regex with repetition vs replaceAll vs replace regex without repetition`

Created: 2 years ago by: Registered User

Go to the latest result

replace regex with repetition

replaceAll

replace regex without repetition

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

replaceAll vs regex replace with and without repetition (version: 0) Benchmark.js

Comparing performance of: replace regex with repetition vs replaceAll vs replace regex without repetition

Created: 2 years ago by: Registered User

Go to the latest result

replace regex with repetition

replaceAll

replace regex without repetition

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

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Comparing performance of: `replace regex with repetition vs replaceAll vs replace regex without repetition`