Benchmark: replaceAll vs regex global replace2

Tests:

replace regex
"this is it".replace(new RegExp(" ", 'g'), "+");
replace All
"this is it".replaceAll(" ", "+");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
replace regex
replace All

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36

Browser/OS: Chrome 141 on Windows

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Test name	Executions per second
replace regex	10943279.0 Ops/sec
replace All	12569389.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 7 months ago):

LLMs can make mistakes. Check important info.

The benchmark you provided compares two different methods for replacing substrings in a string in JavaScript: using a regular expression with the `replace` method and using the `replaceAll` method, which was introduced in ECMAScript 2021 (ES12).

### Test Cases Overview

1. **Regular Expression Replace**
   - **Test Case Name**: `replace regex`
   - **Code**: `"this is it".replace(new RegExp(" ", 'g'), "+");`
   - **Description**: This approach uses the `String.prototype.replace` method with a regular expression. The regular expression `/ /g` is used to identify all occurrences of a space in the string ("this is it") and replace each space with a plus sign ("+").

2. **String ReplaceAll**
   - **Test Case Name**: `replace All`
   - **Code**: `"this is it".replaceAll(" ", "+");`
   - **Description**: This approach utilizes the `String.prototype.replaceAll` method, which is a more straightforward way to replace all instances of a substring in a string. In this case, all spaces in the string are replaced with plus signs.

### Performance Results

The benchmark results show that:
- The `replaceAll` method had an execution rate of approximately **12,569,389 operations per second**.
- The `replace` method with a regex had a rate of approximately **10,943,279 operations per second**.

### Pros and Cons

**Regular Expression Replace:**
- **Pros**:
  - Flexibility: Regular expressions can match complex patterns, not limited to just static substrings.
  - Versatility: Can handle various matching scenarios, such as case insensitive matches, character classes, etc.
  
- **Cons**:
  - Performance: Regular expressions can be slower, especially for simpler replacements like just replacing spaces, due to the overhead of regex processing.
  - Readability: The syntax can be more complex and harder for other developers to understand at a glance.

**String ReplaceAll:**
- **Pros**:
  - Simplicity: The method is straightforward and easy to read, making it very intuitive for simple replacements.
  - Performance: It tends to be faster for straightforward replacements since it does not involve the overhead of the regex engine.
  
- **Cons**:
  - Limited to exact substring matches: If you need more complicated string manipulation, `replaceAll` will not suffice, and regex must be used.

### Other Considerations

- **Browser Compatibility**: `replaceAll` is a newer feature and may not be available in older browsers. Developers need to ensure that the target browsers for their application support ES12.
- **Alternative Methods**: Other alternatives for string replacement could include:
  - Using `split` and `join` methods: `string.split(' ').join('+')`. This approach can sometimes be clearer but may also be less efficient because it creates intermediate arrays.
  - Custom implementation: Developers could write their own function for substring replacement, but this is generally unnecessary given the built-in methods and will likely be less performant.

### Conclusion

In summary, the benchmark demonstrates that for the specific task of replacing spaces with plus signs, the `replaceAll` method is faster and simpler for straightforward replacements, while regular expressions offer wider capabilities at the cost of performance and complexity. When choosing which method to use, developers should consider the specifics of their use case, including performance requirements and the complexity of patterns they need to match.

Related benchmarks:

replaceAll vs regex global replace2 (version: 1)

Comparing performance of: replace regex vs replace All

Created: 7 months ago by: Guest

Jump to the latest result

replace regex

replace All

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 7 months ago):