Benchmark: RegEx.test vs. localStorage.getItem

Script Preparation code:

var string = "Mozilla/5.0 (iPhone; CPU iPhone OS 13_2_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.0.3 Mobile/15E148 Safari/604.1";
var regex = /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini\/i/;
window.localStorage.setItem("is-mobile", true);

Tests:

localStorage.getItem
window.localStorage.getItem("is-mobile");
regex.test
regex.test(string);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
localStorage.getItem
regex.test

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/140.0.0.0 Safari/537.36 Edg/140.0.0.0

Browser/OS: Chrome 140 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
localStorage.getItem	9518552.0 Ops/sec
regex.test	54562520.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the provided benchmark definition and its implications.

**Benchmark Definition**

The benchmark measures the performance difference between two JavaScript functions: `regex.test` and `localStorage.getItem`. The test cases are:

1. `localStorage.getItem`
2. `regex.test`

Both tests use a specific input string, which includes information about a mobile device (e.g., "Android", "iPhone"). This suggests that the benchmark is testing the performance of these two functions when dealing with a mobile-specific scenario.

**Options Compared**

The two options being compared are:

1. **`localStorage.getItem`**: This function retrieves the value stored under the specified key (`"is-mobile"` in this case) from the client-side storage (also known as local storage).
2. **`regex.test`**: This function checks if the specified regular expression pattern matches any characters at the beginning of a string.

**Pros and Cons**

*   **`localStorage.getItem`**:
    *   Pros: Local storage is widely supported, and this method can be more efficient than using regular expressions for simple string matching.
    *   Cons: The performance of `localStorage.getItem` can vary depending on the browser's implementation and the available storage space. Additionally, using local storage might not be suitable for all use cases (e.g., server-side rendering).
*   **`regex.test`**:
    *   Pros: Regular expressions are powerful tools that can handle complex string matching tasks. This method is generally more flexible than `localStorage.getItem`.
    *   Cons: The performance of regular expression tests can be slower due to the complexity of the pattern and the need to compile it before execution.

**Library/Feature Used**

In this benchmark, the following libraries/features are used:

*   **Local Storage (Window.localStorage)**: This is a client-side storage mechanism that allows users to store data locally within their browser.
*   **Regular Expressions (regex)**: This is a powerful pattern-matching system in JavaScript.

**Special JS Features/Syntax**

None mentioned. The benchmark focuses on the performance comparison of two basic JavaScript functions, `localStorage.getItem` and `regex.test`.

**Alternative Approaches**

For similar use cases:

1.  **Server-side storage**: Instead of using local storage, consider storing data on a server and retrieving it via AJAX requests.
2.  **Other string matching methods**: Depending on the specific requirements, other approaches like string interpolation or binary search might be more suitable.

**Additional Considerations**

*   Keep in mind that the performance differences between `localStorage.getItem` and `regex.test` may vary across different browsers and platforms due to variations in implementation.
*   The benchmark's results provide insights into the relative performance of these two functions but do not account for other factors like code complexity, maintainability, or security concerns.

By understanding the benchmark's purpose and options being compared, developers can make informed decisions about when to use `localStorage.getItem` versus regular expressions for string matching tasks.

Related benchmarks:

RegEx.test vs. localStorage.getItem (version: 0)

Comparing performance of: localStorage.getItem vs regex.test

Created: 3 years ago by: Guest

Jump to the latest result

localStorage.getItem

regex.test

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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