Benchmark: replace with global regexp vs replaceAll vs split-join

Tests:

replace with global regexp
"i want to replace all the spaces in this string".replace(/ /g, "_");
replaceAll
"i want to replace all the spaces in this string".replaceAll(" ", "_");
split-join
"i want to replace all the spaces in this string".split(" ").join("_");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
replace with global regexp
replaceAll
split-join

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 14 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36

Browser/OS: Chrome 134 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
replace with global regexp	4336145.0 Ops/sec
replaceAll	3434794.2 Ops/sec
split-join	5454634.5 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 14 days ago):

LLMs can make mistakes. Check important info.

The benchmark "replace with global regexp vs replaceAll vs split-join" assesses three different JavaScript approaches for replacing all spaces in a string with underscores (`_`). The test compares performance across three methods:

1. **Replace with global regexp**
   - **Code:** `\"i want to replace all the spaces in this string\".replace(/ /g, \"_\");`
   - This approach uses a regular expression with the global flag (`g`). It searches for all occurrences of spaces in the string and replaces them with underscores.
   - **Pros:**
     - Concise and straightforward in expressing the replacement operation.
     - Efficient for simple replacements when working with small to medium strings.
   - **Cons:**
     - Regular expressions can be overkill for simple replacements and may introduce unnecessary complexity, especially for developers not familiar with regex syntax.

2. **ReplaceAll**
   - **Code:** `\"i want to replace all the spaces in this string\".replaceAll(\" \", \"_\");`
   - The `replaceAll` method is a newer addition to JavaScript that directly replaces all instances of a specified substring without requiring regular expressions.
   - **Pros:**
     - Simple and clean syntax, making it very readable.
     - It's designed specifically for replacing substrings, potentially leading to clearer intentions in the code.
   - **Cons:**
     - Supported in modern environments but might not work in older browsers, so compatibility issues can arise in legacy systems.

3. **Split-join Method**
   - **Code:** `\"i want to replace all the spaces in this string\".split(\" \").join(\"_\");`
   - This method splits the string into an array using space as the delimiter and then joins the array elements back together using underscores.
   - **Pros:**
     - Very clear and intuitive method, especially for developers less familiar with regular expressions.
     - This approach avoids potential pitfalls of regex but may be less efficient for large strings due to intermediate array creation.
   - **Cons:**
     - May introduce overhead from splitting and then rejoining the string, which can lead to slower performance compared to other methods in cases where performance is critical.

### Performance Insights
Based on the benchmark results:
- **split-join** achieved the highest performance with approximately **5.45 million executions per second**.
- **replace with global regexp** performed next at approximately **4.34 million executions per second**.
- **replaceAll** provided the lowest execution speed at around **3.43 million executions per second**.

### Other Considerations
When choosing which approach to use for string replacements, consider:
- **Readability vs Efficiency:** While regex and the `replaceAll` method are concise, the split-join method may be more intuitive for some developers.
- **Environment Compatibility:** If supporting older JavaScript environments, regex and split-join methods may be more reliable. Conversely, `replaceAll` should be avoided unless targeting modern browsers.
- **Use Case Specificity:** For large datasets or performance-critical applications, it would be advisable to profile and choose the method that balances performance with user-friendliness based on the team's familiarity with the chosen technique.

### Alternatives
Beyond the methods tested, other alternatives involve:
- Using libraries like **Lodash** for string manipulation, which can simplify various string operations but may add a dependency.
- Custom function implementations for specific use cases, especially when handling more complex string manipulation requirements beyond simple replacements.

Related benchmarks:

replace with global regexp vs replaceAll vs split-join (version: 1)

Comparing performance of: replace with global regexp vs replaceAll vs split-join

Created: 14 days ago by: Guest

Jump to the latest result

replace with global regexp

replaceAll

split-join

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 14 days ago):