Benchmark: startswith vs slice 2

Script Preparation code:

s = `hey can i be in the slice`;
sx = `hey can i`
check = `hey can i be in `;
noop = Function.prototype;

function fastStartsWith(s, check) {
	return s.slice(check.length) === check
}

Tests:

startswith
if (s.startsWith(check)) noop();
slice
if (s.slice(check.length) === check) noop();
tetete
if (fastStartsWith(s, check)) noop();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
startswith
slice
tetete

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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Let's break down the provided benchmark and explain what's being tested, compared, and considered.

**Benchmark Overview**

The benchmark measures the performance of three different approaches to check if a string `s` starts with another string `check`. The approaches are:

1. `startsWith`
2. `slice`
3. A custom implementation called `fastStartsWith`

**Approaches Compared**

The three approaches are compared in terms of their execution speed, measured by the number of executions per second.

* `startsWith`: This is a built-in JavaScript method that checks if a string starts with another string.
* `slice`: This method returns a new string containing from the start (default offset 0) to the end (offset length) of the original string. By comparing the result of `s.slice(check.length)` with `check`, we can determine if `s` starts with `check`.
* `fastStartsWith`: This is a custom implementation that checks if `s` starts with `check` by slicing `s` from the start and comparing it with `check`.

**Pros and Cons**

Here are some pros and cons of each approach:

* `startsWith`:
	+ Pros: Built-in method, efficient, easy to use.
	+ Cons: May be slower than custom implementations for very short strings or edge cases.
* `slice`:
	+ Pros: Can be faster than `startsWith` for very short strings, as it avoids the overhead of a built-in method call.
	+ Cons: Requires slicing the original string, which can be inefficient for large strings. The comparison with `check` is also unnecessary if we only care about whether `s` starts with `check`.
* `fastStartsWith`:
	+ Pros: Custom implementation allows for optimized code and edge case handling.
	+ Cons: More verbose than built-in methods, requires manual implementation.

**Library**

None of the approaches use a specific library. The `noop()` function is used in all three implementations to indicate that they are only measuring execution speed and do not have any side effects.

**Special JS Features or Syntax**

* None mentioned.

**Benchmark Preparation Code**

The preparation code sets up the test data:
```javascript
s = 'hey can i be in the slice';
sx = 'hey can i';
check = 'hey can i be in ';
noop = Function.prototype;
```
The `fastStartsWith` implementation is defined separately, as it requires a custom implementation.

**Individual Test Cases**

Each test case measures the execution speed of one specific approach:

* `startswith`: Measuring the performance of the built-in `startsWith` method.
* `slice`: Measuring the performance of comparing `s.slice(check.length)` with `check`.
* `tetete`: Measuring the performance of the custom implementation `fastStartsWith`.

**Alternative Approaches**

Other approaches to check if a string starts with another string might include:

* Using a regular expression: `new RegExp('^' + check).test(s)`
* Using a simple loop: `for (var i = 0; s[i] === check[0]; i++) { ... }`
* Using a different custom implementation, such as using the `indexOf` method or a lookup table.

These alternatives might have their own pros and cons, depending on the specific use case and performance requirements.

Related benchmarks:

startswith vs slice 2 (version: 0)

yeah

Comparing performance of: startswith vs slice vs tetete

Created: 2 years ago by: Guest

Jump to the latest result

startswith

slice

tetete

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):