Benchmark: isNaN vs Number.isNaN vs Self comparison

Script Preparation code:

const a = 0, { isNaN: cachedIsNaN } = Number

Tests:

isNaN
isNaN(a)
Number.isNaN
Number.isNaN(a)
cachedIsNaN
cachedIsNaN(a)
Self comparison
a !== a

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
isNaN
Number.isNaN
cachedIsNaN
Self comparison

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/132.0.0.0 Safari/537.36 OPR/87.0.0.0

Browser/OS: Opera 87 on Android

View result in a separate tab

Test name	Executions per second
isNaN	31567904.0 Ops/sec
Number.isNaN	31265906.0 Ops/sec
cachedIsNaN	30505156.0 Ops/sec
Self comparison	33368616.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):

LLMs can make mistakes. Check important info.

The benchmark titled "isNaN vs Number.isNaN vs Self comparison" is designed to compare the performance of different methods to check for NaN (Not a Number) values in JavaScript. This is particularly useful since NaN is a special numeric value in JavaScript that indicates an undefined or unrepresentable value, especially in floating-point calculations.

### Options Compared:

1. **isNaN(a)**: This is a global function that checks whether the value of `a` is NaN. It coerces the argument into a number and evaluates whether the result is NaN.

2. **Number.isNaN(a)**: A static method available on the global `Number` object that determines whether the value passed is actually NaN without performing any type coercion. It returns true only if the value is of type Number.

3. **cachedIsNaN(a)**: This is essentially a reference to `Number.isNaN`, assigned to `cachedIsNaN` in the preparation code. It aims to provide the same functionality as `Number.isNaN` while avoiding the repeated property lookup from the `Number` object.

4. **a !== a**: This is a self-comparison trick used to determine if the value of `a` is NaN, leveraging the fact that NaN is the only value in JavaScript that is not equal to itself. This method offers a simple and straightforward way to check for NaN.

### Pros/Cons of Different Approaches:

1. **isNaN(a)**
   - **Pros**: Simple to use and widely recognized; works in various contexts.
   - **Cons**: Type coercion can lead to unexpected results, as it will return true for non-numeric values that can be coerced to NaN.

2. **Number.isNaN(a)**
   - **Pros**: More reliable since it does not perform type coercion; returns true only for the true NaN value.
   - **Cons**: Slightly less known compared to the more traditional `isNaN`. May require polyfills in environments that do not support ES6.

3. **cachedIsNaN(a)**
   - **Pros**: Optimizes performance by storing the reference to `Number.isNaN`, avoiding property lookups for each function call.
   - **Cons**: Functionally equivalent to `Number.isNaN`; the performance gain may be minimal in real-world applications.

4. **a !== a**
   - **Pros**: Very fast and clever way to determine NaN; it directly tests the unique property of NaN.
   - **Cons**: May be less readable to some developers; not a canonical method or conventional practice for checking NaN in most codebases.

### Benchmark Results:

From the benchmark results:
- **isNaN** has the highest execution speed at approximately 11.98 million executions per second.
- **Self comparison** is slightly behind at 11.56 million executions per second.
- **cachedIsNaN** follows closely with 10.96 million executions per second.
- **Number.isNaN** is the slowest at 10.18 million executions per second among the four.

### Considerations:

While execution speed is a vital metric in performance-sensitive applications, the choice among these methods should also consider code readability, maintainability, and whether developers are familiar with the methods used.

### Alternative Approaches:

Other alternatives for checking for NaN values include using libraries such as Lodash, which provides utility functions like `_.isNaN()`. This function adds another layer of safety and convenience, especially in situations where checking for NaN becomes part of larger data validation routines. However, it comes with added dependency and potential for overhead compared to native JavaScript methods.

Overall, the choice of method can depend significantly on the context in which it is used, balancing the needs of performance with those of code clarity and maintainability.

Related benchmarks:

isNaN vs Number.isNaN vs Self comparison (version: 1)

Comparing performance of: isNaN vs Number.isNaN vs cachedIsNaN vs Self comparison

Created: 2 months ago by: Guest

Jump to the latest result

isNaN

Number.isNaN

cachedIsNaN

Self comparison

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):