Benchmark: "isNumber" - isNaN vs + vs typeof

Script Preparation code:

var k = "sadasljdaw";

Tests:

isNaN
eval(''); with({}); var r = !Number.isNaN(k);
+
eval(''); with({}); var r = +k !== NaN;
typeof
eval(''); with({}); var r = typeof k !== "number";

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
isNaN
+
typeof

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36

Browser/OS: Chrome 128 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
isNaN	3968174.5 Ops/sec
+	3823263.5 Ops/sec
typeof	5415408.0 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 benchmark and its components.

**Benchmark Definition**
The benchmark measures the performance of three different approaches to check if a value is a number:

1. `isNaN(k)`: checks if the value is not a number (i.e., NaN, or "Not a Number")
2. `+k !== NaN`: converts the value to a number using unary `+` and then checks if it's not equal to NaN
3. `typeof k !== "number"`: uses the `typeof` operator to check if the value is of type "number"

**Options Compared**
The benchmark compares the performance of these three approaches in different scenarios.

* `isNaN(k)`: a simple function call that directly checks if the value is not a number.
* `+k !== NaN`: converts the value to a number using unary `+` and then checks if it's not equal to NaN. This approach has an additional overhead due to the conversion step.
* `typeof k !== "number"`: uses the `typeof` operator to check if the value is of type "number". This approach also has an additional overhead due to the operator call.

**Pros and Cons**

* `isNaN(k)`: simple, direct, and fast, but may not work as expected for certain edge cases (e.g., NaN itself).
* `+k !== NaN`: converts the value to a number, which can lead to precision issues, especially for non-integer values. However, this approach is widely used in JavaScript.
* `typeof k !== "number"`: uses an operator that's not as performance-critical as function calls or unary conversions.

**Library and Special JS Feature**
There are no libraries mentioned in the benchmark definition.

However, it's worth noting that the `Number.isNaN()` function was introduced in ECMAScript 2015 (ES6) to provide a safer alternative to `isNaN()`. This function checks if a value is NaN or not, without relying on the behavior of `isNaN()` for non-numeric values. The benchmark uses this function as an alternative to `isNaN(k)`.

**Other Alternatives**
In addition to the three approaches mentioned in the benchmark, other alternatives could include:

* Using a regular expression (`^\d+$`) to check if a value is a number
* Using a utility library like `lodash.isNumber()` or `moment.isNumber()`
* Using a specialized function like `is-number` from `@stdlib/number-is`

However, these alternatives are not mentioned in the benchmark definition.

Overall, the benchmark provides a useful comparison of different approaches to check if a value is a number, allowing developers to make informed decisions about which approach to use depending on their specific requirements and performance constraints.

Related benchmarks:

"isNumber" - isNaN vs + vs typeof (version: 0)

Comparing performance of: isNaN vs + vs typeof

Created: 4 years ago by: Guest

Jump to the latest result

isNaN

+

typeof

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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