Benchmark: Replace RegExp vs split

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

const testString = "1234-56";

const splitRegExp = /^(\d{4})(?:-\d{1,2})?/;

Tests:

RegExp
testString.replace(splitRegExp, "$1");
Split
testString.split("-")[0];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
RegExp
Split

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36

Browser/OS: Chrome 136 on Windows

View result in a separate tab

Test name	Executions per second
RegExp	2393483.2 Ops/sec
Split	15594101.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 11 months ago):

LLMs can make mistakes. Check important info.

The benchmark provided compares two different approaches for extracting a segment from a string: using a regular expression (RegExp) versus using the `split` method. The performance of these two methods is quantified in terms of how many times they can be executed per second.

### Approaches Compared

1. **Regular Expression (RegExp) Approach**
   - **Test Case**: `testString.replace(splitRegExp, "$1");`
   - **Description**: This approach uses a regex pattern (`/^(\\d{4})(?:-\\d{1,2})?/) to match the input string. It captures the first four digits before the optional hyphen and any subsequent digits, returning the first capture group.
   - **Pros**:
     - Powerful and flexible for complex string patterns.
     - Can perform multiple matches and substitutions in a single call.
   - **Cons**:
     - Regular expressions can be challenging to read and maintain, especially for complex patterns.
     - They often involve additional overhead that may slow down performance for simple tasks.
     - Slightly higher cognitive load when debugging or modifying regex patterns.

2. **String Split Approach**
   - **Test Case**: `testString.split("-")[0];`
   - **Description**: This approach splits the string `testString` at the hyphen and returns the first element of the resulting array, which contains the desired part of the string (the first four digits).
   - **Pros**:
     - Very straightforward and easy to understand.
     - Minimal performance overhead for simple string manipulations.
     - Readable and maintainable code.
   - **Cons**:
     - Limited to simple scenarios where a specific delimiter is known.
     - Less flexible for more complex string extraction needs compared to regex.

### Benchmark Results

The benchmark results show that the string split approach, which executed **15,594,101** times per second, significantly outperforms the regular expression approach, executing only **2,393,483** times per second. This indicates that for this specific string manipulation task, using `split` is far more efficient than using a regex match.

### Considerations

When choosing between these two approaches, developers should consider the complexity of the string manipulation needed:
- For simple operations, such as extracting substrings based on fixed delimiters, the `split` method is clearly the better choice due to its performance and readability.
- When more complex pattern matching is necessary (e.g., validating formats or extracting multiple pieces of data from a string), regular expressions are invaluable despite their performance cost.

### Alternatives

Several other alternatives also exist for string manipulation in JavaScript:
- **Substrings**: Using `substring` or `slice` can be suitable when the positions of characters in the string are known and fixed.
  - Example: `testString.substring(0, 4);`
- **IndexOf and Slice**: Pairing `indexOf` with `slice` can also help in specific scenarios.
  - Example: `testString.slice(0, testString.indexOf("-"));`
- **String Replacement**: The `String.prototype.replace()` method can be used in simpler contexts without regex.
  - Example: `testString.replace("-56", "");`

In general, the choice of method will depend on the specific requirements of the task at hand. For performance-critical applications, even small differences can have meaningful impacts, so profiling different methods is often recommended.

Related benchmarks:

Replace RegExp vs split (version: 1)

Comparing performance of: RegExp vs Split

Created: 11 months ago by: Guest

Jump to the latest result

RegExp

Split

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 11 months ago):