Benchmark: indexOf() === 0 vs lastindexof( ,0) === 0 vs startsWith() vs idx

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;
startsWith
var str = "Hello world, welcome to the universe."; var n = str.startsWith("Hello");
idx
var str = "Hello world, welcome to the universe."; var n = str[0] === 'H' && str[1] === 'e' && str[2] === 'l' && str[3] === 'l' && str[4] === 'o';
idx #2
var str = "Hello world, welcome to the universe."; var n = str[0] == 'H' && str[1] == 'e' && str[2] == 'l' && str[3] == 'l' && str[4] == 'o';
substr
var str = "Hello world, welcome to the universe."; var n = str.substring(0, 5) === 'Hello';

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
lastIndexOf
indexOf
startsWith
idx
idx #2
substr

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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I'll break down the benchmark and its test cases, explaining what's being tested, the options compared, pros and cons of each approach, and other considerations.

**Benchmark Definition**

The benchmark definition is a JSON object that describes the tests to be performed. It includes:

* `Name`: A human-readable name for the benchmark.
* `Description`: An optional description of the benchmark (not provided in this case).
* `Script Preparation Code` and `Html Preparation Code`: Optional scripts or HTML code that may be executed before running the test cases.

**Test Cases**

The benchmark consists of six test cases:

1. **lastIndexOf**
	* Test: `str.lastIndexOf("Hello", 0) === 0`
	* What's being tested: The `lastIndexOf` method returns the index of the last occurrence of a substring within a given string, starting from a specified position.
2. **indexOf**
	* Test: `str.indexOf("Hello") === 0`
	* What's being tested: The `indexOf` method returns the index of the first occurrence of a substring within a string.
3. **startsWith**
	* Test: `str.startsWith("Hello")`
	* What's being tested: The `startsWith` method returns a boolean indicating whether a string starts with a specified value.
4. **idx** (index-based comparison)
	* Test: `str[0] === 'H' && str[1] === 'e' && str[2] === 'l' && str[3] === 'l' && str[4] === 'o';`
	* What's being tested: A manual implementation of string indexing and comparison.
5. **idx #2** (index-based comparison with loose equality)
	* Test: `str[0] == 'H' && str[1] == 'e' && str[2] == 'l' && str[3] == 'l' && str[4] == 'o';`
	* What's being tested: A manual implementation of string indexing and comparison using loose equality operators (`==` instead of `===`).
6. **substr**
	* Test: `str.substring(0, 5) === 'Hello';`
	* What's being tested: The `substring` method returns a new string containing the characters from the beginning to a specified position.

**Comparison of Options**

The test cases compare different approaches for achieving the same result:

* **lastIndexOf**, **indexOf**, and **startsWith**: These methods are built-in JavaScript functions that perform substring searches.
* **idx** and **idx #2**: These tests implement string indexing and comparison manually, using array-like syntax (`str[0]`, `str[1]`, etc.) and loose equality operators (`==` instead of `===`).
* **substr**: This method is a built-in JavaScript function for extracting a substring from a larger string.

**Pros and Cons of Each Approach**

Here are some pros and cons of each approach:

* **lastIndexOf**, **indexOf**, and **startsWith**: Built-in methods, easy to implement, and provide accurate results. However, may be slower than manual implementations.
* **idx** and **idx #2**: Manual implementation can be faster for small strings, but may be slower for larger strings due to the overhead of array-like indexing and loose equality checks.
* **substr**: Built-in method that is efficient and easy to use.

**Other Considerations**

Some additional considerations:

* **Browser differences**: JavaScript methods like `lastIndexOf` and `indexOf` may behave differently across browsers. Test cases should account for these variations.
* **Performance optimizations**: Depending on the use case, manual implementations or built-in methods may be optimized differently for performance. Consider using WebAssembly (WASM) or other optimization techniques for high-performance applications.

I hope this explanation helps clarify the benchmark and its test cases!

Related benchmarks:

indexOf() === 0 vs lastindexof( ,0) === 0 vs startsWith() vs idx (version: 0)

Comparing performance of: lastIndexOf vs indexOf vs startsWith vs idx vs idx #2 vs substr

Created: 4 years ago by: Guest

Jump to the latest result

lastIndexOf

indexOf

startsWith

idx

idx #2

substr

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):