Benchmark: Tyepof vs isFinite vs Number.isFinite

Script Preparation code:

var a = {};

Tests:

typeof
for(let i =0; i < 1000000; i++) { const b = typeof a === 'number'; }
Number.isFinite
for(let i =0; i < 1000000; i++) { const b = Number.isFinite(a); }
isFinite
for(let i =0; i < 1000000; i++) { const b = isFinite(a); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
typeof
Number.isFinite
isFinite

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36

Browser/OS: Chrome 126 on Windows

View result in a separate tab

Test name	Executions per second
typeof	3.1 Ops/sec
Number.isFinite	1.2 Ops/sec
isFinite	0.9 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 provided benchmark and explain what's being tested.

**Benchmark Definition**

The JSON represents a JavaScript microbenchmarking test case with three different approaches to compare:

1. `typeof`
2. `Number.isFinite`
3. `isFinite`

All three approaches are used to check if a variable `a` is a finite number. The script preparation code initializes an empty object `var a = {};`, which will be used as the input for these tests.

**Options Compared**

The options being compared in this test case are:

1. Using the `typeof` operator to determine if `a` is a finite number.
2. Using the `Number.isFinite()` function from JavaScript's built-in library to check if `a` is a finite number.
3. Using a custom function `isFinite()` which is not part of JavaScript's standard library, but likely implemented by the creator of this benchmark.

**Pros and Cons**

Here are some pros and cons for each approach:

1. **typeof**: This operator returns a string describing the type of the variable `a`, such as `"object"`. While it may seem like a quick way to check if `a` is finite, using `typeof` can be misleading if `a` is an object with a `toString()` method that returns a non-finite value. Additionally, this approach can be slow because it involves calling the `toString()` method.
2. **Number.isFinite()**: This function checks if a number is finite (i.e., not NaN or Infinity). It's a reliable way to check if a variable is a finite number, but it may still return false positives if `a` has a non-finite value as part of its object properties.
3. **isFinite()**: Since this custom function is not part of JavaScript's standard library, its implementation and behavior are unknown. This makes it difficult to analyze or compare the results.

**Library: Number.isFinite()**

The `Number.isFinite()` function is a built-in JavaScript method that checks if a number is finite (i.e., not NaN or Infinity). It's used to determine if a variable is a finite number, similar to the `typeof` operator in this benchmark. However, as mentioned earlier, it may still return false positives if `a` has a non-finite value as part of its object properties.

**Other Considerations**

The use of custom functions like `isFinite()` can be problematic because they introduce uncertainty and potential bugs into the test results. The creator of this benchmark likely intended to compare the performance of these built-in methods, but the presence of the custom function makes it difficult to draw conclusions about its implementation.

In general, when creating microbenchmarks, it's essential to choose a consistent set of inputs and implementations to ensure that the results are reliable and comparable. Using built-in JavaScript methods like `Number.isFinite()` is generally a good idea, as they provide a standardized way to perform common operations.

**Alternatives**

If you were to create similar benchmarks in the future, you could consider using alternative approaches or modifying this benchmark to make it more comprehensive. Some options might include:

1. Using different types of inputs (e.g., numbers, strings, objects) to test various edge cases.
2. Comparing the performance of different built-in methods or libraries (e.g., `Number.isFinite()` vs. a custom implementation).
3. Testing the performance of these operations in different contexts (e.g., web, Node.js, browser extensions).

By considering alternative approaches and modifying this benchmark to make it more comprehensive, you can create more reliable and informative microbenchmarks for your JavaScript applications.

Related benchmarks:

Tyepof vs isFinite vs Number.isFinite (version: 0)

Comparing performance of: typeof vs Number.isFinite vs isFinite

Created: one year ago by: Guest

Jump to the latest result

typeof

Number.isFinite

isFinite

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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