Benchmark: String toLowerCase vs. Regex test

Tests:

toLowerCase
const strings = [ 'abcd', 'ABCD', 'Abcd', 'defg', 'defG', '1234', 'blah', 'nine', 'TEN', ]; strings.forEach((el) => { el.toLowerCase() === el; });
RegExp
const strings = [ 'abcd', 'ABCD', 'Abcd', 'defg', 'defG', '1234', 'blah', 'nine', 'TEN', ]; strings.forEach((el) => { /[A-Z]/.test(el); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
toLowerCase
RegExp

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:144.0) Gecko/20100101 Firefox/144.0

Browser/OS: Firefox 144 on Windows

View result in a separate tab

Test name	Executions per second
toLowerCase	54067336.0 Ops/sec
RegExp	6502918.5 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided JSON represents a JavaScript benchmark that compares two approaches for checking whether a string contains upper-case letters: the `toLowerCase()` method and regular expressions (RegEx).

**Approach 1: `toLowerCase()` Method**

The first approach uses the `toLowerCase()` method, which converts a string to lowercase. This method is implemented in the browser's built-in JavaScript engine.

**Pros of using the `toLowerCase()` method:**

* Fast execution speed, as it is optimized for performance.
* Simple and straightforward implementation.
* No additional dependencies or libraries are required.

**Cons of using the `toLowerCase()` method:**

* May not be suitable for strings that contain non-ASCII characters (e.g., accented letters).
* May not provide the desired level of case insensitivity, as it only converts to lowercase.

**Approach 2: Regular Expressions (RegEx)**

The second approach uses RegEx to match uppercase letters in a string. This method is implemented using a regular expression engine that is part of the browser's JavaScript engine or a separate library.

**Pros of using RegEx:**

* Provides case-insensitive matching, allowing for accurate detection of upper-case letters.
* Can be used with non-ASCII characters, making it more versatile than the `toLowerCase()` method.

**Cons of using RegEx:**

* May be slower than the `toLowerCase()` method due to the overhead of compiling and executing regular expressions.
* Requires additional dependencies or libraries (e.g., the ` RegExp` object).
* Can be more complex to implement, especially for developers without experience with regular expressions.

**Library Used in the Benchmark**

In this benchmark, the `RegExp` object is used to implement the RegEx approach. The `RegExp` constructor takes two arguments: a pattern and an optional flags parameter. In this case, the pattern `[A-Z]` matches any uppercase letter.

**Special JS Feature or Syntax**

There is no special JavaScript feature or syntax used in this benchmark beyond regular expressions. However, it's worth noting that modern JavaScript engines often provide additional features and optimizations for specific use cases, such as string manipulation.

**Other Alternatives**

If you're interested in exploring other approaches for checking whether a string contains upper-case letters, here are some alternatives:

* Using a custom implementation with bitwise operations (e.g., using `charCodeAt()` and `>>> 0`).
* Using a library like Lodash or Underscore.js that provides utility functions for working with strings.
* Using a different data structure, such as an array of uppercase letters, to check for presence.

Keep in mind that these alternatives may offer trade-offs in terms of performance, readability, and maintainability.

Related benchmarks:

String toLowerCase vs. Regex test (version: 0)

Different methods of checking whether a string contains upper-case letters

Comparing performance of: toLowerCase vs RegExp

Created: 3 years ago by: Guest

Jump to the latest result

toLowerCase

RegExp

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):