Benchmark: replaceAll vs non-regex replace

Script Preparation code:

String.prototype.replaceAll = function(search, replacement) {
    var target = this;
    return target.replace(new RegExp(search, 'g'), replacement);
};

Tests:

replace regex
"this is it".replace(" ", "+");
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: 6 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:142.0) Gecko/20100101 Firefox/142.0

Browser/OS: Firefox 142 on Linux

View result in a separate tab

Test name	Executions per second
replace regex	6550511.5 Ops/sec
replace All	1500586.0 Ops/sec

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

LLMs can make mistakes. Check important info.

The benchmark provided compares two different methods of replacing text in a string in JavaScript: a regex-based replacement using the `String.prototype.replace` method and a custom method called `replaceAll` that utilizes regex under the hood but is designed specifically for replacing all occurrences of a substring.

### Options Compared

1. **Regex Replace (`replace` method)**: 
   - **Test Case**: `"this is it".replace(" ", "+");`
   - This method uses the `replace` function to find the first occurrence of a space character and replace it with a plus sign.

2. **Custom Replace All (`replaceAll` method)**:
   - **Test Case**: `"this is it".replaceAll(" ", "+");`
   - `replaceAll` is defined in the benchmark preparation code as a custom implementation that converts the string into a regular expression that globally replaces all occurrences of the specified character (in this case, all spaces) with the given replacement character.

### Pros and Cons

#### Regex Replace

- **Pros**:
  - Simplicity: Easy to read and understand for replacing a single instance.
  - No additional overhead from constructing a regular expression.
  
- **Cons**:
  - Only replaces the first occurrence, which limits its utility for scenarios where multiple replacements are required.
  - Requires a more complex solution (looping or additional logic) for replacing multiple occurrences, which can affect performance.

#### Custom Replace All

- **Pros**:
  - Can handle multiple replacements in one call, making it more suitable for strings with many duplicate substrings.
  - Encapsulates logic for global replacement internally.

- **Cons**:
  - Slightly more complex as it utilizes regular expressions, which may be less performant depending on the implementation.
  - The custom implementation, as provided, may have overhead due to creating a new `RegExp` object.

### Benchmark Results

The benchmark results indicate the performance of each method:

- **replace method**: 
  - Executions per second: **23,884,992.0**
  
- **replaceAll method**:
  - Executions per second: **5,509,809.0**

From the results, it’s clear that the regex-based `replace` method is significantly faster than the `replaceAll` method. This difference may be attributed to the overhead introduced by the custom global regex replacement.

### Considerations

When deciding between these two methods, programmers must consider both readability and performance. If the use case requires replacing a single occurrence, `String.replace` is more efficient. However, when needing to replace all occurrences of a substring, it's beneficial to weigh the performance hit against the required functionality.

### Alternatives

1. **Using `replaceAll` (Standard)**: 
   - ES2021 introduced the `String.prototype.replaceAll` method natively in JavaScript, which handles replacing all instances of a substring or regular expression more efficiently and simply than the custom method shown.

2. **Using Regular Expressions Directly**: 
   - A standard regex approach can also be employed, such as using `string.replace(/ /g, "+")`, which would directly replace all spaces globally without a custom function.
   
3. **Loop Methods**: 
   - In cases of performance-critical applications, and for granular control, developers might consider alternative methods that manually handle replacements, particularly for specific use cases or custom behaviors which may not be covered by standard methods.

Ultimately, the choice of method should align with the specific requirements of the application in terms of performance, readability, and maintainability.

Related benchmarks:

replaceAll vs non-regex replace (version: 1)

Comparing performance of: replace regex vs replace All

Created: one year 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 one year ago):