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

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); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

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

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and benchmark code to understand what's being tested.

**Benchmark Definition**

The benchmark definition is an object that provides information about the test case. In this case, it contains:

* `Name`: A unique name for the benchmark.
* `Description`: An optional description of the benchmark, which is empty in this case.
* `Script Preparation Code` and `Html Preparation Code`: These are code snippets that are executed before running each test case.

In this case, the script preparation code defines a regular expression (`pat`) and assigns it to a variable. The pattern `/^http.?:\/\//\.com/` matches URLs that start with "http://" (with an optional colon and forward slash) followed by ".com".

**Test Cases**

The benchmark contains four test cases, each represented as an object:

* `Benchmark Definition`: A string containing the JavaScript code to be executed for the test case.
* `Test Name`: A unique name for the test case.

Here's a brief explanation of each test case:

1. **index**: This test case uses the regular expression (`pat`) directly in the loop condition: `pat[0] === "/" && pat[pat.length - 1] === "/"`.
2. **charAt**: This test case uses the `charAt()` method to access the first and last characters of the string: `pat.charAt(0) === "/" && pat.charAt(pat.length - 1) === "/"`.
3. **startsWith & endsWith**: This test case uses the `startsWith()` and `endsWith()` methods to check if the string starts with and ends with "/": `pat.startsWith("/") && pat.endsWith("/")`.
4. **slice**: This test case uses the `slice()` method to extract a substring from the original string: `pat.slice(0, 1) === "/" && pat.slice(-1) === "/"`.
5. **regex test**: This test case uses the `test()` method of the regular expression object to check if the pattern matches: `(/^\/\.+\/$`).test(pat).

**Comparison of Options**

Here's a comparison of the options used in each test case:

* **Direct access vs. method calls**: The `index` and `slice` test cases use direct access to the string elements (`pat[0]`, `pat[pat.length - 1]`) versus method calls (`charAt()`, `slice()`). Method calls are generally slower because they involve an additional function call.
* **Regular expression vs. built-in methods**: The `index`, `charAt`, and `regex test` test cases use regular expressions, while the `startsWith & endsWith` test case uses built-in string methods. Regular expressions can be slower than built-in methods due to their complexity and overhead.

**Pros and Cons**

Here are some pros and cons of each approach:

* **Direct access vs. method calls**: Pros: faster execution; Cons: less readable, more prone to errors.
* **Regular expression vs. built-in methods**: Pros: flexible, can handle complex patterns; Cons: slower execution, may be overkill for simple cases.

**Other Considerations**

When designing microbenchmarks like this one, it's essential to consider factors such as:

* **Simplified input data**: The benchmark uses a fixed string pattern (`pat`) and only checks the first and last characters. Real-world strings often have more complex patterns.
* **Loop iterations**: The benchmark uses a fixed number of loop iterations (`count = 1000`). In reality, this value can vary greatly depending on the specific use case.
* **Browser variability**: The benchmark results are reported for a single browser version (Firefox 122). Real-world testing should consider multiple browsers and versions.

**Alternatives**

If you're interested in exploring alternative approaches or testing other JavaScript features, here are some options:

* **Benchmarking libraries**: Consider using established benchmarking libraries like Benchmark.js or Microbenchmark.
* **JavaScript engines**: Test the performance of different JavaScript engines like V8 (Chrome), SpiderMonkey (Firefox), or Safari's JavaScript engine.
* **String manipulation APIs**: Experiment with other string manipulation APIs, such as Unicode Code Points or internationalization features.

Keep in mind that microbenchmarks are often used to identify performance bottlenecks and optimize specific code paths. Always consider the context and requirements of your project when designing and running benchmarks.

Latest run results:

Run details: (Test run date: 10 months 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	2433405.0 Ops/sec
charAt	2456048.0 Ops/sec
startsWith & endsWith	2356459.2 Ops/sec
slice	2438017.8 Ops/sec
regex test	50709.3 Ops/sec

Related benchmarks:

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

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

Created: 10 months ago by: Guest

Jump to the latest result

index

charAt

startsWith & endsWith

slice

regex test

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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