Benchmark: Compare isNaN vs Hack Checking

Script Preparation code:

var arr = new Float64Array(10000);
for(var i=0; i<arr.length;i++){arr[i]=Math.random()>0.5?Math.random():NaN}
var count = 0;

Tests:

isNaN
for(var i=0; i<arr.length;i++){ if(isNaN(arr[i]))count++; }
hack checking
for(var i=0; i<arr.length;i++){ if(arr[i]!==arr[i])count++; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
isNaN
hack checking

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36

Browser/OS: Chrome 129 on Windows

View result in a separate tab

Test name	Executions per second
isNaN	243.4 Ops/sec
hack checking	291.5 Ops/sec

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 Description**

The benchmark is designed to compare two approaches for checking if a value is Not A Number (NaN) in JavaScript:

1. **isNaN**: This function checks if a value is NaN using its internal implementation, which uses a combination of bitwise operations and comparing the value with itself.
2. **Hack Checking**: This approach uses a simple and naive method to check if a value is NaN by comparing it with itself. However, this method can be misleading as it may return false positives (i.e., returning true for values that are not exactly NaN).

**Options Compared**

The two approaches are being compared in terms of their performance, specifically the number of executions per second on different browsers and devices.

**Pros and Cons**

* **isNaN**: Pros:
	+ Implemented by the JavaScript engine itself, making it likely to be optimized.
	+ Less prone to false positives compared to Hack Checking.
Cons:
	+ Its internal implementation may vary between engines or versions.
* **Hack Checking**: Pros:
	+ Simple to implement and understand.
Cons:
	+ Prone to false positives due to its simple nature.
	+ May not be optimized for performance.

**Library**

In this benchmark, no specific library is used. The implementations are built-in to JavaScript.

**Special JS Feature or Syntax**

There's no special feature or syntax being tested here. Both approaches rely on standard JavaScript functionality.

**Other Alternatives**

If you're looking for alternative ways to check if a value is NaN in JavaScript, you could consider using:

* **Number.isNaN()**: This function was introduced in ECMAScript 2015 (ES6) and provides a more robust way to check for NaN values. It uses the same internal implementation as isNaN but with additional checks.
* **BigInt** or **Number** types: In modern JavaScript, you can use the BigInt type to represent integers and avoid common pitfalls associated with NaN values.

**Benchmark Preparation Code**

The preparation code is quite simple:
```javascript
var arr = new Float64Array(10000);
for (var i = 0; i < arr.length; i++) {
  if (Math.random() > 0.5) {
    arr[i] = Math.random();
  } else {
    arr[i] = NaN;
  }
}
var count = 0;
```
This code creates an array of 10,000 floating-point values and sets half of them to a random number between 0 and 1 (inclusive), while the other half is set to NaN. The variable `count` will be incremented whenever isNaN or Hack Checking detects a NaN value in the array.

**Individual Test Cases**

There are two test cases:

* **isNaN**: This case uses the standard isNaN function.
* **Hack Checking**: This case uses a simple and naive method to check for NaN values by comparing them with themselves.

Related benchmarks:

Compare isNaN vs Hack Checking (version: 0)

Comparing performance of: isNaN vs hack checking

Created: one year ago by: Guest

Jump to the latest result

isNaN

hack checking

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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