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mwdev - index vs lastindexof
(version: 0)
Benchmark.js
Comparing performance of:
lastIndexOf vs indexOf
Created:
2 years ago
by:
Guest
Go to the latest result
Tests:
lastIndexOf
var str = "Hello world, welcome to the universe."; var n = str.lastIndexOf("Hello", 0) === 0;
indexOf
var str = "Hello world, welcome to the universe."; var n = str.indexOf("Hello") === 0;
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
lastIndexOf
indexOf
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:120.0) Gecko/20100101 Firefox/120.0
Browser/OS:
Firefox 120 on Windows
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<iframe src="https://measurethat.net/Embed?id=486841" width="100%" height="500px"></iframe>
indexOf
584.8M/s
lastIndexOf
45.6M/s
View exact numbers
Test name
Executions per second
✓
indexOf
584,792,128 Ops/sec
lastIndexOf
45,552,232 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark and explain what's being tested. **Benchmark Definition** The benchmark definition is a JSON object that specifies the test to be performed. In this case, there are two individual test cases: 1. `lastIndexOf`: Tests the lastIndexOf method of a string. 2. `indexOf`: Tests the indexOf method of a string. Both tests use a fixed input string: `"Hello world, welcome to the universe."`. **Options Compared** The benchmark is comparing two different approaches for checking if the index of the specified substring matches the starting position: 1. **lastIndexOf**: Uses the lastIndexOf method, which returns the highest index found in the string that satisfies the condition. 2. **indexOf**: Uses the indexOf method, which returns the first index found in the string that satisfies the condition. **Pros and Cons** * **lastIndexOf**: + Pros: May be faster if the substring is not found at the beginning of the string, since it can stop searching once it finds a match. + Cons: Can be slower for strings where the substring is found at the beginning, as it has to search the entire string. * **indexOf**: + Pros: Faster for strings where the substring is found at the beginning, since it only needs to check one position. + Cons: May be slower if the substring is not found, as it has to search the entire string. **Other Considerations** The benchmark may also consider other factors such as: * String length: Longer strings might affect performance due to increased memory allocation and copying. * Substring length: Shorter substrings might have different performance characteristics compared to longer ones. * Browser and platform variations: Different browsers and platforms might optimize these methods differently, affecting the results. **Library/Functionality** There is no external library or functionality used in this benchmark. The tests are purely relying on built-in JavaScript methods (`lastIndexOf` and `indexOf`) of strings. **Special JS Features/Syntax** None mentioned explicitly, but it's worth noting that this benchmark assumes a specific JavaScript engine (JavaScript 1.8.5, as indicated by the `rv:120.0` version in the benchmark result) and does not account for potential variations across different engines or versions. **Alternatives** If you were to implement an alternative benchmark, you might consider: * Using different string manipulation methods, such as regular expressions or array indices. * Comparing performance with different browsers, platforms, or devices. * Adding more test cases to cover edge cases, such as empty strings, null inputs, or Unicode characters. * Analyzing the output of the benchmark to identify potential bottlenecks or areas for optimization.
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