Benchmark: instanceof vs typeof 22

Script Preparation code:

var x = 15

Tests:

typeof
typeof x === 'number'
typeof no function
x !== undefined
typeof and test attribute
x>=0

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
typeof
typeof no function
typeof and test attribute

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the explanation of what's being tested in this benchmark.

**Overview**
The provided JSON represents a JavaScript microbenchmark that tests three different approaches for comparing values with the `typeof` operator: `instanceof`, `typeof`, and a custom test attribute. The goal is to determine which approach is faster in a specific scenario.

**Options being compared**

1. **`instanceof`**: This method checks if an object is an instance of a particular constructor function. In this case, it's used to check if the value `x` is a number.
2. **`typeof`**: This operator returns a string indicating the type of its operand. For example, for a number, it would return `"number"`.
3. **Custom test attribute**: A custom test attribute is defined using the `Script Preparation Code`, which sets `x` to `15`. The custom test checks if `x` has a certain value using a test attribute.

**Pros and Cons**

*   **`instanceof`**:
    *   Pros: Fast, as it only requires a single comparison with the constructor function.
    *   Cons: May not work as expected for primitive values (e.g., numbers) since they don't have constructors.
*   **`typeof`**:
    *   Pros: Works well for both object and primitive values. However, it involves an additional overhead due to string comparison.
    *   Cons: May be slower than `instanceof` due to the overhead of string creation.
*   **Custom test attribute**:
    *   Pros: Provides a flexible way to define custom tests using attributes. Can be useful for more complex scenarios.
    *   Cons: Requires manual setup and maintenance, which can add complexity.

**Library usage**

The `Script Preparation Code` uses the `var x = 15;` statement, which is a basic JavaScript variable declaration syntax. No specific library or framework is required for this simple test case.

**Special JS feature or syntax**

There are no special JavaScript features or syntaxes mentioned in this benchmark. It only relies on standard JavaScript operators and data types.

**Alternative approaches**

If you're looking for alternative ways to compare values with `typeof`, here are a few options:

1.  **Using `instanceof` with a constructor function**: Instead of using the built-in `Number` constructor, you can create your own constructor function or use an existing one (e.g., `Math`). This approach is similar to what's being tested in this benchmark.
2.  **Using a library like Lodash**: If you need more advanced comparison logic or want to simplify repetitive code, consider using a library like Lodash, which provides utility functions for working with JavaScript values and objects.
3.  **Using a test framework like Jest**: For more complex tests or when working with asynchronous code, you can use a test framework like Jest. This would allow you to write more structured tests and leverage features like mocking and parameterized testing.

Keep in mind that the choice of approach depends on your specific requirements and project constraints.

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/108.0.0.0 Safari/537.36

Browser/OS: Chrome 108 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
typeof	16380332.0 Ops/sec
typeof no function	6066183.5 Ops/sec
typeof and test attribute	16786696.0 Ops/sec

Related benchmarks:

instanceof vs typeof 22 (version: 0)

Comparing performance of: typeof vs typeof no function vs typeof and test attribute

Created: one year ago by: Guest

Jump to the latest result

typeof

typeof no function

typeof and test attribute

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):