Benchmark: typeof number vs. Number.isNan vs. isNan vs self comparison

Tests:

typeof
typeof 5 === 'number'
Number.isNan
Number.isNaN(5)
isNaN
isNaN(5)
Self comparison
5 !== 5

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
typeof
Number.isNan
isNaN
Self comparison

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36

Browser/OS: Chrome 119 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
typeof	1003869952.0 Ops/sec
Number.isNan	17585696.0 Ops/sec
isNaN	17496074.0 Ops/sec
Self comparison	1001263872.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided JSON represents a JavaScript microbenchmarking test case created on MeasureThat.net. The benchmark tests four different approaches to check if a value is a number: `typeof`, `Number.isNaN`, `isNaN`, and self-comparison using the `!==` operator.

**Options Compared**

1. **`typeof 5 === 'number'`**: This approach uses the `typeof` operator in combination with a string comparison (`===`) to check if the value is a number. The `typeof` operator returns a string indicating the type of the variable, and by comparing it to `'number'`, we can determine if the value is indeed a number.
2. **`Number.isNaN(5)`**: This approach uses the `Number.isNaN()` function, which checks if a given value is NaN (Not a Number).
3. **`isNaN(5)`**: This approach uses the `isNaN()` function, which returns `true` if the value is NaN and `false` otherwise.
4. **`5 !== 5`**: This approach uses self-comparison with the `!==` operator to check if the value is not equal to itself (i.e., it's a number).

**Pros and Cons of Each Approach**

1. **`typeof 5 === 'number'`**:
	* Pros: Fast and simple.
	* Cons: May be slower for non-numeric values, as `typeof` returns a string literal, which can lead to unnecessary overhead.
2. **`Number.isNaN(5)`**: This approach is not available in older browsers that don't support ECMAScript 2017 (ES7) standard.
3. **`isNaN(5)`**:
	* Pros: Similar speed to `typeof` for numeric values, as it only checks if the value is NaN.
	* Cons: May be slower for non-numeric values, as it's a separate function call.
4. **`5 !== 5`**: This approach is simple and fast, but it assumes that the value being compared is a number.

**Library Used**

None of these approaches rely on external libraries.

**Special JS Feature or Syntax**

There are no special features or syntax used in this benchmark.

**Considerations**

* For numeric values, all four approaches have similar performance.
* For non-numeric values (e.g., strings), the `typeof` approach may be slower due to unnecessary string comparisons.
* Older browsers may not support the `Number.isNaN()` and `isNaN()` functions.

**Other Alternatives**

If you need a more robust or modern way of checking if a value is a number, consider using:

1. **`Number` constructor**: Creates a new number object from a given value.
2. **`instanceof Number` operator**: Checks if an object is an instance of the `Number` class.

However, these alternatives may not be supported in older browsers and may have different performance characteristics compared to the original approaches tested here.

Related benchmarks:

typeof number vs. Number.isNan vs. isNan vs self comparison (version: 0)

Comparing performance of: typeof vs Number.isNan vs isNaN vs Self comparison

Created: 2 years ago by: Guest

Jump to the latest result

typeof

Number.isNan

isNaN

Self comparison

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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