Benchmark: Skip Substr if length is less

Script Preparation code:

const strings = [];

for (let i = 0; i < 5000; ++i) {
  const randomString = (Math.random() * 100000).toString();
  strings.push(randomString);
}

window.strings = strings;

Tests:

Substr conditionally
window.strings.forEach(string => { if (typeof string === 'string') { const newString = string.length < 250000 ? string : string.substr(0, 250000); } });
Substr every time
window.strings.forEach(string => { if (typeof string === 'string') { const newString = string.substr(0, 250000); } });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Substr conditionally
Substr every time

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explain what's being tested.

**Benchmark Definition**

The benchmark definition consists of two scripts:

1. `Script Preparation Code`: This script generates an array of 5000 random strings, which are then assigned to the `window.strings` property. This is done to simulate a real-world scenario where the benchmark might be run multiple times with different inputs.
2. `Html Preparation Code`: This field is empty, indicating that no HTML code needs to be prepared for this benchmark.

**Individual Test Cases**

There are two test cases:

1. **Substr conditionally**: This script loops through each string in `window.strings` and checks if the type of the string is `'string'`. If it is, it then checks if the length of the string is less than 250000. If both conditions are true, it truncates the string using the `substr()` method with a length of 250000.
2. **Substr every time**: This script loops through each string in `window.strings` and applies the same logic as before, but without checking if the type of the string is `'string'`. It always uses the `substr()` method to truncate the strings.

**Library:**

In both scripts, the `window` object is used. In JavaScript, the `window` object represents the global scope of a web page, providing access to various properties and methods related to the browser environment.

**Special JS feature or syntax:**

There are no special features or syntaxes mentioned in these scripts. However, it's worth noting that the use of `substr()` is an older method for string manipulation in JavaScript. A more modern approach would be to use the `slice()` method or template literals.

**Options Compared**

In this benchmark, two approaches are compared:

1. **Substr conditionally**: This approach checks if the type of the string is `'string'` before applying the truncation.
2. **Substr every time**: This approach always applies the truncation without checking the type of the string.

**Pros and Cons:**

* **Substr conditionally**:
	+ Pros: May be more efficient if most strings are already validated to be strings, reducing unnecessary checks.
	+ Cons: Requires an additional check for the string type, which might introduce some overhead.
* **Substr every time**:
	+ Pros: Simplifies the code by eliminating the need for a separate type check.
	+ Cons: May lead to slower performance if most strings are indeed valid, as the type check is unnecessary.

**Other Considerations**

* The use of `substr()` instead of more modern methods like `slice()` or template literals might affect the performance and readability of the code.
* The random string generation in the script preparation code adds some noise to the benchmark results, making it harder to isolate the specific effect of the substr() method.

**Alternatives**

If you were to rewrite this benchmark with different approaches, here are a few alternatives:

1. Use modern methods like `slice()` or template literals for string manipulation.
2. Compare other optimization techniques, such as:
	* Using `String.prototype.slice()` instead of `substr()`.
	* Comparing the performance of `substr()` with and without type checks.
	* Examining the impact of different string length thresholds on performance.

Keep in mind that these alternatives would require modifications to the benchmark definition and test cases.

Related benchmarks:

Skip Substr if length is less (version: 0)

Skipping the Substr method if possible

Comparing performance of: Substr conditionally vs Substr every time

Created: 4 years ago by: Guest

Jump to the latest result

Substr conditionally

Substr every time

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):