Benchmark: Index Test - MeasureThat.net

Script Preparation code:

window.exampleFileName = `${"file".repeat(5)}.ext`;

Tests:

.indexOf
window.exampleFileName.indexOf('.');
.lastIndexOf
window.exampleFileName.lastIndexOf('.');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
.indexOf
.lastIndexOf

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/112.0

Browser/OS: Firefox 112 on Linux

View result in a separate tab

Test name	Executions per second
.indexOf	12750414.0 Ops/sec
.lastIndexOf	11941664.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided JSON and explain what's being tested, compared, and the pros/cons of different approaches.

**Benchmark Definition**

The benchmark is defined by a JSON object with three properties:

* `Name`: The name of the benchmark, which is "Index Test".
* `Description`: An empty string indicating no description for this benchmark.
* `Script Preparation Code`: A code snippet that assigns a variable `window.exampleFileName` to a string containing 5 occurrences of the string `"file.ext"`. This code prepares the script environment for running.
* `Html Preparation Code`: An empty string indicating no HTML preparation is needed.

**Individual Test Cases**

The benchmark consists of two test cases:

1. `".indexOf"`: The benchmark definition is `window.exampleFileName.indexOf('.')`, which measures the performance of the `indexOf` method.
2. `".lastIndexOf"`: The benchmark definition is `window.exampleFileName.lastIndexOf('.')`, which measures the performance of the `lastIndexOf` method.

**Library and Purpose**

The `exampleFileName` variable appears to be using a technique called string interpolation, which allows the value of a variable to be inserted into a string. In this case, it's used to create a dynamic string with multiple occurrences of `"file.ext"`.

There is no explicit library mentioned in the code. However, the use of `window` suggests that this code might be running in a browser environment or a similar context where the global object (usually referred to as `window`) provides access to various properties and functions.

**Special JavaScript Features/Syntax**

The code uses string interpolation (`${"file".repeat(5)}.ext`) to create a dynamic string. This is not a standard JavaScript feature, but rather an extension of template literals introduced in ECMAScript 2015 (ES6). The `repeat()` method was also added to the `String` prototype in ES2017.

**Other Considerations**

Both test cases are measuring the performance of simple indexing methods on a string variable. The difference lies in whether the index is found from the start (`indexOf`) or from the end (`lastIndexOf`) of the string.

**Pros and Cons of Different Approaches**

* **`indexOf`**: This method returns the first occurrence of the specified character (in this case, `.`). It's faster than `lastIndexOf` because it has to search less characters.
	+ Pros: Generally faster due to its shorter search range.
	+ Cons: May not find all occurrences if the string contains multiple consecutive matches.
* **`lastIndexOf`**: This method returns the last occurrence of the specified character. It's slower than `indexOf` because it searches from both ends towards the center.
	+ Pros: Finds all occurrences, not just the first one.
	+ Cons: Generally slower due to its longer search range.

**Other Alternatives**

If you wanted to test similar indexing methods on different string variables or with different characters, you could modify the benchmark definition and script preparation code accordingly. For example:

* `window.exampleFileName.includes('.')`
* `window.exampleFileName.match(/\./g)`

Keep in mind that these alternatives might not provide identical results due to differences in character matching and performance characteristics.

I hope this explanation helps!

Related benchmarks:

Index Test (version: 0)

Comparing performance of: .indexOf vs .lastIndexOf

Created: one year ago by: Guest

Jump to the latest result

.indexOf

.lastIndexOf

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):