Benchmark: isNaN vs regex test for stringify number check

Script Preparation code:

var value = "123"; 
var regex = /^\d+$/;

Tests:

regex
regex.test(value)
isNan with parseInt
isNaN(parseInt(value, 10))
isNan with Number
isNaN(Number(value))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
regex
isNan with parseInt
isNan with Number

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/107.0.0.0 Safari/537.36

Browser/OS: Chrome 107 on Windows

View result in a separate tab

Test name	Executions per second
regex	6586123.5 Ops/sec
isNan with parseInt	3280535.2 Ops/sec
isNan with Number	3412328.8 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark tests two different approaches to check if a string representation of a number is not a valid number (isNaN). The approaches are:

1. Using a regular expression (`regex.test(value)`).
2. Using the `isNaN()` function with either `parseInt()` or `Number()`.

**Options Compared**

The benchmark compares the performance of these three options:

* `regex.test(value)`: uses a regular expression to check if the string matches the pattern of a valid number.
* `isNaN(parseInt(value, 10))`: converts the string to an integer using `parseInt()` with radix 10, and then checks if the result is NaN (not a number).
* `isNaN(Number(value))`: directly converts the string to a number using `Number()`, and then checks if the result is NaN.

**Pros and Cons of Each Approach**

1. **regex.test(value)**:
	* Pros: Regular expressions can be more flexible and powerful for complex pattern matching.
	* Cons: May be slower than the other two approaches, as it involves parsing the string according to the regular expression rules.
2. **isNaN(parseInt(value, 10))**:
	* Pros: Can handle strings that contain numeric characters but are not valid numbers (e.g., "123abc").
	* Cons: Converts the string to an integer using a specific radix, which may not be desirable in all cases.
3. **isNaN(Number(value))**:
	* Pros: Directly converts the string to a number without any intermediate steps, which can be faster and more straightforward.
	* Cons: May not handle non-numeric strings correctly (e.g., "hello").

**Library and Purpose**

The `Number()` function is a built-in JavaScript function that attempts to convert a string to a number. It returns NaN if the conversion fails.

**Special JS Feature/Syntax**

None of the test cases use any special JavaScript features or syntax, so there's no additional explanation needed.

**Other Alternatives**

If you're looking for alternative approaches, here are a few options:

* Using `isNaN()` with ` parseFloat(value)` instead of `parseInt()`: This would attempt to convert the string to a float instead of an integer.
* Using a dedicated library like `moment.js` or `date-fns` to parse dates and numbers from strings: These libraries provide more advanced features for working with date and number formats, but may add unnecessary complexity.

Overall, the benchmark provides a simple and straightforward test case for comparing the performance of different approaches to check if a string representation of a number is not valid.

Related benchmarks:

isNaN vs regex test for stringify number check (version: 0)

Comparing performance of: regex vs isNan with parseInt vs isNan with Number

Created: 2 years ago by: Guest

Jump to the latest result

regex

isNan with parseInt

isNan with Number

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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