Benchmark: isFinite vs typeof

Script Preparation code:

varsToCheck = [3, 3.14, "some string", null, undefined];
count = 0;

Tests:

isFinite
varsToCheck.forEach(function(v){ if(Number.isFinite(v)) { count++ } });
typeof === "number"
varsToCheck.forEach(function(v){ if(typeof v === "number") { count++ } });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
isFinite
typeof === "number"

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 19 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.1.1 Safari/605.1.15

Browser/OS: Safari 18 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
isFinite	44903268.0 Ops/sec
typeof === "number"	86601448.0 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 its options.

**Benchmark Definition**

The benchmark is testing two different ways to check if a variable is either finite or a number:

1. `Number.isFinite(v)`
2. `typeof v === "number"`

**Options Comparison**

Both approaches are used to determine if a value is a number, but they have some differences:

*   **`Number.isFinite(v)`**: This method checks if the value is a finite number (i.e., not NaN or infinity). It returns a boolean value (`true` if the value is finite, `false` otherwise).
    *   **Pros**:
        *   More accurate for checking whether a value is a specific numerical type.
        *   Faster execution time because it only checks for finiteness and does not perform an explicit type conversion like `typeof`.
    *   **Cons**: This method returns `true` for NaN values, but `typeof v === "number"` would return `"NaN"`, so you must always check the value separately.
*   `typeof v === "number"`
    *   **Pros**:
        *   More straightforward to understand and use because it directly checks if a variable is an exact string representation of 'number'.
        *   If used carefully, can provide a more explicit error message when checking for invalid types.
    *   **Cons**: This method returns `"NaN"` (if the value is NaN), which could lead to confusion about what type of number was tested.

**Pros and Cons Analysis**

*   Choose `Number.isFinite(v)` if you want:
    *   Faster execution speed
    *   More accurate results
    *   Less risk of returning incorrect values (NaN or infinity)
*   Choose `typeof v === "number"` if you want:
    *   A more explicit, clear code that says exactly what it is checking for
    *   More straightforward to implement a custom error handling strategy

**Library Usage**

No external libraries are explicitly used in the benchmark. However, keep in mind that when using JavaScript in your own projects, there are several commonly-used libraries and tools you might run into.

**Special JS Feature or Syntax**

None of the test cases use special JS features or syntax beyond standard JavaScript language elements such as loops (`forEach`), variables, numbers, strings, and conditionals.

Related benchmarks:

isFinite vs typeof (version: 0)

Comparing performance of: isFinite vs typeof === "number"

Created: 3 years ago by: Guest

Jump to the latest result

isFinite

typeof === "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):