Benchmark: declare test - MeasureThat.net

Script Preparation code:

var func1 = function(obj) {
	if (obj !== undefined) { return obj.x; }
}
var func2 = function(obj) {
	if (obj) { return obj.x; }
}

var ar1 = [];
var ar2 = [];

for (let i = 0; i < 1e5; i++) {
	ar1.push(Math.random() < 0.5 ? void 0 : {'x': Math.random()});
	ar2.push(Math.random() < 0.5 ? void 0 : {'x': Math.random()});
}

for (let i = 0; i < 1e3; ++i) {
	func1(Math.random() < 0.5 ? void 0 : {'x': Math.random()});
	func2(Math.random() < 0.5 ? void 0 : {'x': Math.random()});
}

Tests:

func2
for (let i = 0; i < 1e5; ++i) { func2(ar1[i]); }
func1
for (let i = 0; i < 1e5; ++i) { func1(ar1[i]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
func2
func1

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark definition and test cases, explaining what is being tested, the options compared, pros and cons of those approaches, library usage, special JavaScript features or syntax, alternatives, and other considerations.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmark. It includes:

1. **Script Preparation Code**: This section defines two functions, `func1` and `func2`, which take an object `obj` as input. The functions check if the object is defined (`obj !== undefined`) and return its property `x`. Additionally, it creates two arrays `ar1` and `ar2` with 100,000 elements each, where each element is either an empty object or a random object with a single `x` property.
2. **Html Preparation Code**: This section is empty (`null`), which means no HTML code is provided for the benchmark.

**Individual Test Cases**

The JSON includes two test cases:

1. **func2**: The benchmark definition is a loop that iterates 100,000 times, calling `func2` with an element from `ar1`.
2. **func1**: The benchmark definition is similar to the first test case but calls `func1` instead of `func2`.

**Options Compared**

In this benchmark, two options are being compared:

* `func2`: Returns the value of `x` if the object is defined (`obj !== undefined`). This approach assumes that the object's existence affects its value.
* `func1`: Also returns the value of `x`, but it uses an explicit check for `undefined`. However, in modern JavaScript, nullish coalescing (explained below) would be a more efficient way to achieve this.

**Pros and Cons**

* **func2**: Pros:
	+ Simple and easy to understand.
	+ Does not rely on the object's existence affecting its value.
Cons:
	+ May return `undefined` if the object is falsy (e.g., null, 0, "", etc.).
	+ Can lead to unexpected behavior when dealing with objects that may be falsy but still have a defined `x`.
* **func1**: Pros:
	+ More predictable and robust than `func2`, especially when dealing with falsy objects.
Cons:
	+ Uses an explicit check for `undefined`, which can make the code harder to read.

**Nullish Coalescing (Optional)**

The nullish coalescing operator (`??`) is a modern JavaScript feature that was introduced in ECMAScript 2020. It allows you to provide a default value if the expression on the left-hand side is either `null` or `undefined`.

Example:
```javascript
let x = obj?.x ?? 'default value';
```
In this case, if `obj.x` is `undefined`, the expression will return `'default value'`.

Using nullish coalescing would make `func1` more efficient and robust than `func2`. However, it's not mentioned in the original benchmark definition.

**Library Usage**

There are no libraries explicitly mentioned in the provided JSON. However, the use of modern JavaScript features like nullish coalescing (if available) relies on standard library support.

**Special JavaScript Features or Syntax**

None are mentioned in the provided JSON. The benchmark focuses on basic JavaScript functionality and data structures.

**Alternatives**

If you wanted to compare these two approaches using a different method, you could:

1. Compare their performance with other functions that achieve similar results, such as `obj?.x || 'default value'`.
2. Use a more comprehensive benchmarking framework like Benchmark.js or Microbenchmark.js, which provide additional features and customization options.

In summary, the provided JSON represents a JavaScript microbenchmark that compares two approaches for accessing an object's property `x`: using explicit checks (`func1`) versus assuming the object's existence affects its value (`func2`).

Latest run results:

Run details: (Test run date: 9 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36

Browser/OS: Chrome 121 on Windows

View result in a separate tab

Test name	Executions per second
func2	65.2 Ops/sec
func1	34.3 Ops/sec

Related benchmarks:

declare test (version: 8)

Comparing performance of: func2 vs func1

Created: 9 months ago by: Registered User

Jump to the latest result

func2

func1

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):