Benchmark: isNull function vs pure

Script Preparation code:

function isNull(anObj) {
  return anObj == null;
}
var aStr = "asdfljbsflaskdnflkbsadf";

Tests:

Pure Box
var test = aStr == null;
Function
var test = isNull(aStr);
Pure
var test = aStr === null;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Pure Box
Function
Pure

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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 its options.

**Benchmark Definition**

The benchmark tests three different approaches to check if a variable is null or not:

1. **Pure Box**: `var test = aStr == null;`
2. **Function**: `var test = isNull(aStr);` (where `isNull` is a custom function defined in the script preparation code)
3. **Pure**: `var test = aStr === null;`

**Library and Custom Function**

The custom function `isNull(anObj)` is used in the "Function" approach. This function simply checks if the input object `anObj` is equal to null using the loose equality operator (`==`). The purpose of this library is to provide a simple way to check for null values.

**Comparison Options**

Here's a summary of each option:

1. **Pure Box**: This method uses the loose equality operator (`==`) to compare the value of `aStr` with null. The `==` operator performs type coercion, which means it will return true even if `aStr` is not exactly null (e.g., if it's an empty string). This approach may lead to false positives.
2. **Function**: This method uses a custom function `isNull(anObj)` to check for null values. The `isNull` function simply checks if the input object is equal to null using the loose equality operator (`==`). While this approach provides a clear and explicit way to check for null values, it may not be as efficient as other methods.
3. **Pure**: This method uses the strict equality operator (`===`) to compare the value of `aStr` with null. The `===` operator performs type coercion, but in this case, since `aStr` is a string and null is an object, the comparison will always return false.

**Pros and Cons**

Here's a summary of each approach:

1. **Pure Box**: Pros: simple and easy to read; Cons: may lead to false positives due to type coercion.
2. **Function**: Pros: provides a clear and explicit way to check for null values; Cons: may not be as efficient as other methods.
3. **Pure**: Pros: avoids type coercion, ensuring accurate results; Cons: may require more parentheses and careful syntax.

**Other Considerations**

When writing benchmarks like this one, consider the following:

* Use meaningful variable names and comments to make the code easy to understand.
* Avoid using global variables or functions that modify external state.
* Keep the benchmark script simple and focused on testing a single aspect of performance.
* Use relevant unit tests or assertion libraries to verify expected results.

**Alternatives**

Other approaches to checking for null values in JavaScript include:

1. **Using `typeof`**: `var test = typeof aStr === 'object' && aStr === null;`
2. **Using `instanceof`**: `var test = aStr instanceof Object && aStr === null;`
3. **Using `&&` with `null`**: `var test = aStr !== undefined && aStr !== null;`

Each of these alternatives has its own trade-offs and use cases, but they can provide more accurate results than the loose equality operators used in the benchmark.

Related benchmarks:

isNull function vs pure (version: 0)

Comparing performance of: Pure Box vs Function vs Pure

Created: 5 years ago by: Guest

Jump to the latest result

Pure Box

Function

Pure

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):