Benchmark: starts with vs regex

HTML Preparation code:

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

Script Preparation code:

let regex = /^abc.*$/

Tests:

startsWith
'abc123'.startsWith('abc')
regex
regex.test('abc123')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
startsWith
regex

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:128.0) Gecko/20100101 Firefox/128.0

Browser/OS: Firefox 128 on Windows

View result in a separate tab

Test name	Executions per second
startsWith	865011968.0 Ops/sec
regex	27415198.0 Ops/sec

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

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON measures the performance of two different approaches for checking whether a string starts with a specific substring: using the `startsWith()` method and using a regular expression (`regex`).

### Options Compared

1. **`startsWith()` Method**:
   - **Test Case**: `'abc123'.startsWith('abc')`
   - **Purpose**: This method is a straightforward way to check if a string begins with a specified substring. It takes one argument (the substring) and returns a boolean value (`true` or `false`).

2. **Regular Expression**:
   - **Test Case**: `regex.test('abc123')`
   - **Purpose**: This approach uses a regular expression to achieve the same goal. The regex pattern defined in the preparation code, `let regex = /^abc.*$/`, matches any string that starts with 'abc'. The `test` method of the regex returns `true` or `false` depending on whether there's a match.

### Pros and Cons

#### `startsWith()` Method
- **Pros**:
  - Clear and concise: The intent is immediately understandable.
  - Performance: Typically optimized for speed in most modern JavaScript engines.
  - Readability: Easier to read and maintain, especially for developers who may not be familiar with regular expressions.

- **Cons**:
  - Less flexible: It can only check static substrings and does not support complex patterns or conditions.

#### Regular Expression
- **Pros**:
  - Flexibility: Regular expressions can match complex patterns, allowing for more sophisticated validation.
  - Power: Can be very powerful for pattern matching beyond simple substring scenarios.

- **Cons**:
  - Performance: Generally slower than direct string methods, especially for simple checks, as regex engines need to interpret the pattern.
  - Complexity: Might be less readable for those unfamiliar with regex syntax, leading to potential maintenance issues.

### Other Considerations

- **Readability vs Performance**: In scenarios demanding high performance with simple checks, `startsWith()` is often the preferred choice due to its clarity and speed. Conversely, when matching complex string patterns or rules, regex is indispensable despite the potential performance cost.
  
- **Library and Syntax**: No external libraries are used here, and the syntax is pure JavaScript. The benchmark operates directly in the JavaScript environment, making use of standard language features.

### Alternatives

While these two methods are commonly used for the specific task of checking string prefixes, other alternatives might include:

- **`indexOf()` Method**: `abc123`.indexOf('abc') === 0` could achieve a similar result by checking if the substring starts at index `0`. However, it lacks the semantic clarity of `startsWith()`.
  
- **String Slicing**: Another approach could involve comparing the sliced portion of the string: `'abc123'.substring(0, 3) === 'abc'`. This is less efficient and readable compared to `startsWith()`.

In summary, this benchmark provides critical insights into the performance differences between two approaches, helping developers make informed choices based on the specific requirements of their applications.

Related benchmarks:

starts with vs regex (version: 1)

Comparing performance of: startsWith vs regex

Created: one year ago by: Guest

Jump to the latest result

startsWith

regex

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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