Benchmark: replace with global regexp vs replaceAll vs split-join v2

Script Preparation code:

const str = "i want to replace all the spaces in this string"
const space = " "
const und = " "
const regExp = / /g

Tests:

replace with global regexp
str.replace(regExp, und);
replaceAll
str.replaceAll(space, und);
split-join
str.split(space).join(und);

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: one year 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	4372663.5 Ops/sec
replaceAll	3416406.8 Ops/sec
split-join	5444278.5 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

The benchmark provided compares three different methods for replacing spaces in a string using JavaScript. These methods are:

1. **Using a Global Regular Expression**: 
   ```javascript
   str.replace(regExp, und);
   ```
   In this approach, a global regular expression (regex) is defined to match all spaces in the target string. The `replace` method then substitutes these spaces with a specified replacement string (in this case, `und`, which denotes a space).

**Pros**:
   - Versatile: Regular expressions can be customized to handle complex pattern matching beyond simple replacements.
   - Efficient for large strings with multiple occurrences of patterns.

**Cons**:
   - Performance overhead: Regex operations can be slower in cases of simple replacements compared to more straightforward methods.
   - Readability: Regular expressions can be cryptic and hard to understand for developers not well-versed in regex syntax.

2. **Using `replaceAll`**:
   ```javascript
   str.replaceAll(space, und);
   ```
   This method leverages the `replaceAll()` function, which was introduced in ECMAScript 2021 (ES12). It directly replaces all instances of the specified substring (`space`) with the replacement string (`und`).

**Pros**:
   - Simplicity: Clear syntax that is easy to read and understand.
   - Intuitive: Designed specifically for replacing all instances of a substring without needing to compile a regex.

**Cons**:
   - Limited to direct substring replacement: It cannot handle complex pattern matching like regular expressions.
   - Browser compatibility: Older browsers that do not support ES12 may not work with this method.

3. **Using `split` and `join`**:
   ```javascript
   str.split(space).join(und);
   ```
   This method splits the string into an array using `space` as a delimiter and then joins the resulting array back into a string with `und` as the separator.

**Pros**:
   - Performance: Can be more efficient for straightforward string replacements, especially for large strings.
   - Flexible: Can easily alter the way the string is manipulated (for example, adding additional processing steps on the array).

**Cons**:
   - More verbose operation: Requires two method calls.
   - Memory overhead: Creates an intermediate array, which can increase memory usage compared to in-place replacements.

### Benchmark Results:
The benchmark results show the number of executions per second for each method using Chrome 134 on Mac OS X 10.15.7:

- **Split-Join**: 5,444,278.5 executions/second (fastest)
- **Replace with Global RegExp**: 4,372,663.5 executions/second
- **ReplaceAll**: 3,416,406.75 executions/second (slowest)
  
### Summary of Alternatives:
Other alternatives for string manipulation in JavaScript may include:
- **Using String Replace with an Inline Function**: For more complex replacements where conditional logic is needed.
- **Using Libraries**: There are libraries like Lodash that provide utility functions for string manipulation, though this may be overkill for simple string replacements.

In conclusion, the choice of method depends on the use case: if performance is critical and the operation is simple, `split-join` may be best. If clarity and maintainability are priorities, `replaceAll` is preferable, especially in modern environments supporting ES12. However, for complex pattern matching requirements, using regular expressions is invaluable. Each method has its unique pros and cons, and understanding these will allow developers to make informed decisions.

Related benchmarks:

replace with global regexp vs replaceAll vs split-join v2 (version: 1)

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

Created: one year ago by: Registered User

Jump to the latest result

replace with global regexp

replaceAll

split-join

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):