Benchmark: String replace using regex vs string (2)

Script Preparation code:

var string = 'test the test {message} test test test test message test test message test test test test test test message'
var regExp = new RegExp('{message}');

Tests:

replace by regex
var res = string.replace(regExp, '.')
replace via string
var res = string.replace('{message}', '.');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
replace by regex
replace via string

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 11 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser/OS: Chrome 135 on Windows

View result in a separate tab

Test name	Executions per second
replace by regex	30516674.0 Ops/sec
replace via string	38268836.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 12 days ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON compares two different methods of string replacement in JavaScript: using a regular expression (`replace by regex`) and using a direct string literal (`replace via string`). Specifically, it examines how efficiently each method performs within a given context.

### Benchmark Breakdown

#### Test Cases Compared
1. **replace by regex**: 
   - **Implementation**: `var res = string.replace(regExp, '.');`
   - **Description**: This method uses a regular expression to locate the `{message}` placeholder in the input string and replaces it with a dot (`.`).
   
2. **replace via string**: 
   - **Implementation**: `var res = string.replace('{message}', '.');`
   - **Description**: This method directly replaces the `{message}` substring in the input string with a dot (`.`) without any regular expression processing.

### Pros and Cons

#### Regular Expression Method
**Pros**:
- **Flexibility**: Regular expressions are powerful and can handle complex pattern matching (e.g., matching variations of a string, case sensitivity, etc.).
- **Dynamic Patterns**: If `{message}` was dynamic or involved varied formatting, regex could accommodate these needs through pattern definitions.

**Cons**:
- **Performance Overhead**: The regex engine introduces overhead, which can result in slower execution, particularly for simple replacements.
- **Complexity**: Writing and reading regex patterns can be difficult for developers not familiar with regex syntax.

#### Direct String Replacement Method
**Pros**:
- **Simplicity & Readability**: The direct string replacement is straightforward, making it easier for developers to understand at a glance.
- **Faster Execution**: Generally, for simple string replacements, this method has a performance edge over regular expressions due to less computational overhead.

**Cons**:
- **Limited Functionality**: This method can only perform straightforward substring replacements and does not support complex matching scenarios.
- **Fixed Patterns**: It struggles if replacements need to account for dynamic or variable forms of the string.

### Benchmark Results Summary
Based on the latest benchmark results:
- The **direct string replacement** method (`replace via string`) achieved approximately **13,793,889 executions per second**.
- The **regular expression method** (`replace by regex`) had a lower performance of around **11,238,374 executions per second**.

Consequently, the direct string replacement is faster than the regular expression approach in this particular scenario.

### Other Considerations
- **Use Case Specificity**: The more efficient method to use depends on the specific use case. For static replacements, using the direct method is optimal. However, when the need arises for complex matching, regex may become necessary despite its performance cost.
- **JavaScript Engine Variability**: Performance may vary based on the JavaScript engine and the context in which the code runs (browser type and version). It is important for benchmarks to consider multiple environments if performance consistency is a concern.

### Alternatives to Consider
1. **String.prototype.split and Array.prototype.join**: For specific cases, one could split a string based on the target substring and then join the resulting array, which can sometimes be more efficient.
2. **String.replaceAll Method**: If replacing multiple occurrences is required in a modern environment, using `replaceAll` could be a consideration (though it still relies on a similar underlying mechanism).

In conclusion, while both string replacement methods serve the same overall function, their suitability greatly depends on the specifics of the task, including complexity, performance requirements, and developer familiarity with toolsets like regular expressions.

Related benchmarks:

String replace using regex vs string (2) (version: 1)

Comparing performance of: replace by regex vs replace via string

Created: 12 days ago by: Guest

Jump to the latest result

replace by regex

replace via string

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 12 days ago):