Benchmark: for vs lastindexof

Tests:

lastIndexOf
var str = "Hello world, welcome to the universe."; var n = str.lastIndexOf("o");
indexOf
var str = "Hello world, welcome to the universe."; var n = lastIndexOf(str, 'o') function lastIndexOf(str, sbj){ for(let i=str.length; i !== 0; i-- ) { if(str[n] === sbj){ return i } }}

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 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36

Browser/OS: Chrome 123 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
lastIndexOf	47626756.0 Ops/sec
indexOf	981397.1 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 benchmark and explain what's being tested, compared, and some pros and cons of different approaches.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark that compares two approaches for finding the last index of a substring in a string:

1. Using the `lastIndexOf` method.
2. Implementing an `indexOf` function with custom logic to find the last index.

**Script Preparation Code and HTML Preparation Code**

Since both scripts are essentially comparing two methods, there is no specific script preparation code or HTML preparation code provided in the JSON. This suggests that the benchmark is simply testing the performance of these two approaches without any additional setup or configuration.

**Library and Custom Functions**

The `lastIndexOf` method is a built-in JavaScript function, which means it's a part of the standard library and doesn't require any external libraries to be included in the test environment.

However, the `indexOf` function is custom-implemented for this benchmark. This suggests that the developer wanted to compare the performance of the built-in `lastIndexOf` method with their own implementation.

**JavaScript Features and Syntax**

There are no special JavaScript features or syntax being tested in this benchmark. The code only uses standard JavaScript syntax, so there's nothing specific to note about the language itself.

**Comparison Options**

The two options being compared are:

1. Using the `lastIndexOf` method.
2. Implementing an `indexOf` function with custom logic to find the last index.

**Pros and Cons of Different Approaches**

**LastIndexOf Method**

Pros:

* Fast and efficient implementation, optimized for performance.
* Built-in JavaScript function, so no additional setup is required.

Cons:

* May not be as customizable or flexible as a custom implementation.
* Dependence on the underlying engine and implementation details.

**Custom IndexedOf Function**

Pros:

* Can be customized to suit specific requirements or optimization needs.
* Control over the implementation details can lead to better performance or flexibility.

Cons:

* Requires more code and setup, which can increase complexity.
* May not be as optimized for performance as a built-in function.

**Other Considerations**

In addition to these options, other factors that might affect benchmark results include:

* The specific use case or scenario being tested (e.g., finding the last index in a loop vs. a single call).
* The size and complexity of the input strings.
* The target browser or environment (e.g., desktop vs. mobile).

**Other Alternatives**

If you were to design an alternative benchmark, you might consider comparing other approaches for finding the last index of a substring in JavaScript, such as:

1. Using regular expressions (regex).
2. Implementing a binary search algorithm.
3. Utilizing a third-party library or framework.

These alternatives would require additional setup and code changes, but could provide more comprehensive insights into the performance characteristics of different approaches.

Related benchmarks:

for vs lastindexof (version: 0)

Comparing performance of: lastIndexOf vs indexOf

Created: 5 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):