Benchmark: Check first and last char loop charAt startsWith slice regex.test 2

Script Preparation code:

var pat = "/^http.?:\/\/.+\.com/";
var count = 1000;

Tests:

index
for (var i = 0; i < count; i++) { pat[0] === "/" && pat[pat.length - 1] === "/"; }
charAt
for (var i = 0; i < count; i++) { pat.charAt(0) === "/" && pat.charAt(pat.length - 1) === "/"; }
startsWith & endsWith
for (var i = 0; i < count; i++) { pat.startsWith("/") && pat.endsWith("/"); }
slice
for (var i = 0; i < count; i++) { pat.slice(0, 1) === "/" && pat.slice(-1) === "/"; }
regex test
for (var i = 0; i < count; i++) { (/^\/.+\/$/).test(pat); }
at
for (var i = 0; i < count; i++) { pat.at(0) === "/" && pat.at(-1) === "/"; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
index
charAt
startsWith & endsWith
slice
regex test
at

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:122.0) Gecko/20100101 Firefox/122.0

Browser/OS: Firefox 122 on Windows

View result in a separate tab

Test name	Executions per second
index	2489455.8 Ops/sec
charAt	2453752.0 Ops/sec
startsWith & endsWith	2346453.2 Ops/sec
slice	2541703.2 Ops/sec
regex test	50963.0 Ops/sec
at	121011.5 Ops/sec

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

LLMs can make mistakes. Check important info.

The provided JSON represents a JavaScript microbenchmark on MeasureThat.net, which allows users to compare the performance of different approaches for testing the first and last character of a string in various ways.

**Benchmarked methods:**

1. **charAt()**: The `charAt()` method is used to extract a single character from a string at the specified index (0-based). In this benchmark, it's used to check if the first and last characters are '/'.
2. **slice()**: The `slice()` method returns a new string containing a subset of characters from the original string. It can be used to extract a portion of a string and then compare its contents with an expected value (in this case, '/').
3. **startsWith()** and **endsWith()**: These two methods are part of the String prototype in JavaScript. `startsWith()` checks if the string starts with a specified value, while `endsWith()` checks if the string ends with a specified value.
4. **regex.test()**: This method uses a regular expression to test if a match is found at the start of the string.

**Comparison and pros/cons:**

*   **charAt()**: This approach provides direct access to individual characters in the string, making it straightforward and efficient. However, it might be less convenient for other scenarios or when working with non-ASCII characters.
*   **slice()**: While this method is versatile, using `slice()` to extract a single character can lead to unnecessary overhead due to creating new strings. Additionally, this approach may not perform as well on very large input strings.
*   **startsWith()** and **endsWith()**: These methods are more convenient than `charAt()` or `slice()`, but they have limitations: `startsWith()` checks from the start of the string, while `endsWith()` checks from the end. Neither handles edge cases like an empty string perfectly.
*   **regex.test()**: Using a regular expression can be an elegant solution for matching patterns, especially if you need to perform more complex tests. However, it might incur overhead due to the additional complexity and processing required by the regex engine.

**Other considerations:**

*   **Browser differences**: The benchmark results show variations in execution performance across different browsers (Firefox 122) running on a desktop platform. This highlights the importance of considering browser-specific nuances and optimizations.
*   **Operating system and device effects**: Some test cases exhibit significant variations, suggesting that factors like operating system or device might impact performance.

**Alternatives:**

If you're looking for alternatives to these methods, consider the following:

*   **String.prototype.includes()**: While not directly comparing characters at specific positions, this method provides a simple way to search for a value within a string.
*   **String.prototype.localeCompare()**: This method is more powerful than the above methods, allowing comparison of strings based on their locale-specific conventions and character encoding.

Related benchmarks:

Check first and last char loop charAt startsWith slice regex.test 2 (version: 0)

Comparing performance of: index vs charAt vs startsWith & endsWith vs slice vs regex test vs at

Created: 2 years ago by: Guest

Jump to the latest result

index

charAt

startsWith & endsWith

slice

regex test

at

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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