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Index Test
(version: 0)
Comparing performance of:
.indexOf vs .lastIndexOf
Created:
3 years ago
by:
Guest
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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>
Run tests (2)
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Test case name
Result
.indexOf
.lastIndexOf
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
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:
Filename and extension
Benchmark getting file extension
index vs lastindexof (last index)
URI has No Extension
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