Benchmark: native string replaceAll vs regex replace

Tests:

replaceAll
"this is it".replaceAll(" ", "+");
replace
"this is it".replace(/ /g, "+");
replaceAll (regex)
"this is it".replaceAll(/ /g, "+");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
replaceAll
replace
replaceAll (regex)

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/147.0.0.0 Safari/537.36 Edg/147.0.0.0

Browser/OS: Chrome 147 on Windows

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Test name	Executions per second
replaceAll	5227379.0 Ops/sec
replace	5932414.0 Ops/sec
replaceAll (regex)	4031235.2 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 8 months ago):

LLMs can make mistakes. Check important info.

The benchmark provided compares the performance of three different methods of replacing characters in a string in JavaScript: `replaceAll` with a string argument, `replace` with a regular expression, and `replaceAll` with a regular expression.

### Tested Options:

1. **String `replaceAll` Method:**
   - **Benchmark Definition:** `"this is it".replaceAll(" ", "+")`
   - **Description:** This method replaces all instances of the specified substring (in this case, a space) with another substring (a plus sign `+`).
   - **Performance Result:** 8,839,795 executions per second.
   - **Pros:**
     - Simple and direct when replacing static substrings.
     - Readable and concise syntax.
   - **Cons:**
     - Cannot use regular expressions directly, limiting its flexibility compared to regex-based methods.

2. **Regex `replace` Method:**
   - **Benchmark Definition:** `"this is it".replace(/ /g, "+")`
   - **Description:** This method uses a regular expression to find all instances of spaces (`/ /g`, where `g` stands for "global") and replaces them with a plus sign.
   - **Performance Result:** 1,635,206.125 executions per second.
   - **Pros:**
     - Very powerful and flexible; can match complex patterns beyond simple substrings.
   - **Cons:**
     - Slightly more complex syntax and less performant for simple tasks compared to `replaceAll`.
     - Regular expressions can be harder to read and maintain for those unfamiliar with regex syntax.

3. **Regex `replaceAll` Method:**
   - **Benchmark Definition:** `"this is it".replaceAll(/ /g, "+")`
   - **Description:** This attempts to use `replaceAll` with a regex pattern to match spaces.
   - **Performance Result:** 1,319,616.875 executions per second.
   - **Pros:**
     - Combines the benefits of both methods by allowing regex while maintaining the simplicity of `replaceAll`.
   - **Cons:**
     - Older JavaScript environments may not support `replaceAll` with regex well, which could lead to compatibility issues.
     - Potentially confusing for users who expect `replaceAll` to only accept strings.

### Other Considerations:
- The benchmark results clearly show that the native string method `replaceAll` has superior performance compared to both regex methods. This is informally indicative of how optimized specific string methods can be in JavaScript engines.
- Regular expressions, while powerful, involve overhead that can lead to decreased performance—especially if the operation does not need to handle complex patterns.
  
### Alternatives:
- **Using a Simple Loop**: For very basic replacements, one might also consider using a loop that constructs a new string. However, this approach is typically less performant than built-in methods and usually more verbose.
- **String Libraries**: Consider using libraries like Lodash or Underscore.js, which can encapsulate string functionality, though this may add unnecessary weight if you only need a single string operation.
- **Template Literals or String Interpolation**: While not directly relevant to replacing strings, these features enable building strings in a more readable way when concatenating static values.

These benchmarks allow developers to choose the most efficient method based on specific use cases while considering the trade-offs related to readability, maintainability, and performance.

Related benchmarks:

native string replaceAll vs regex replace (version: 1)

Comparing performance of: replaceAll vs replace vs replaceAll (regex)

Created: 8 months ago by: Guest

Jump to the latest result

replaceAll

replace

replaceAll (regex)

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 8 months ago):