Benchmark: index vs startsWith

Tests:

lastIndexOf
var str = "Hello world, welcome to the universe."; var n = str.lastIndexOf("welcome");
startsWith
var str = "Hello world, welcome to the universe."; var n = str.startsWith("welcome");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
lastIndexOf
startsWith

Fastest: N/A

Slowest: N/A

Latest run results:

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

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**Overview of the Benchmark**

The provided benchmark is designed to compare the performance of two JavaScript methods: `str.lastIndexOf("welcome")` and `str.startsWith("welcome")`. The benchmark is run on various browsers and devices, with multiple executions per second.

**Script Preparation Code**

In this case, the script preparation code is empty, which means that no additional setup or initialization code is executed before running the test cases.

**Html Preparation Code**

The html preparation code is also empty, which implies that no HTML-specific setup is required for these tests.

**Benchmark Definition and Test Cases**

There are two test cases:

1. **lastIndexOf**: This test case uses a string `str` with the value `"Hello world, welcome to the universe."`. The method `str.lastIndexOf("welcome")` is called on this string, which returns the index of the last occurrence of the substring `"welcome"`.
2. **startsWith**: Similar to the first test case, but this time the method `str.startsWith("welcome")` is called on the same string `str`, returning a boolean indicating whether the string starts with the specified substring.

**Library and Special JavaScript Features**

Neither of the test cases uses any external libraries or special JavaScript features. The code is straightforward and relies only on built-in JavaScript methods.

**Options Comparison**

The two methods, `lastIndexOf` and `startsWith`, differ in their behavior:

* **lastIndexOf**: Returns the index of the last occurrence of a substring within the string.
	+ Pros: Can be useful for finding the position of a specific value within a larger dataset.
	+ Cons: May have performance implications if used on large datasets, as it requires searching from the end of the string.
* **startsWith**: Returns a boolean indicating whether the string starts with a specified substring.
	+ Pros: Efficient and fast, as it only checks the first few characters of the string.
	+ Cons: Does not provide information about the position or occurrence count of the starting substring.

**Other Considerations**

When choosing between `lastIndexOf` and `startsWith`, consider the specific use case:

* If you need to find the position of a specific value within a larger dataset, use `lastIndexOf`.
* If you only care about determining whether the string starts with a particular substring, use `startsWith`.

**Alternative Approaches**

If neither `lastIndexOf` nor `startsWith` meets your requirements, you may consider alternative approaches:

* Use a different data structure, such as an array or object, to store and search for values.
* Implement custom indexing or searching algorithms using JavaScript.
* Utilize external libraries or frameworks that provide optimized string manipulation functions.

Keep in mind that the choice of method depends on the specific problem requirements and performance constraints.

Related benchmarks:

index vs startsWith (version: 0)

Comparing performance of: lastIndexOf vs startsWith

Created: 5 years ago by: Guest

Jump to the latest result

lastIndexOf

startsWith

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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