Benchmark: mwdev - index vs lastindexof

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>

Previous results

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

View result in a separate tab

Test name	Executions per second
lastIndexOf	45552232.0 Ops/sec
indexOf	584792128.0 Ops/sec

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

LLMs can make mistakes. Check important info.

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.

Related benchmarks:

mwdev - index vs lastindexof (version: 0)

Comparing performance of: lastIndexOf vs indexOf

Created: 2 years ago by: Guest

Jump to the latest result

lastIndexOf

indexOf

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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