Benchmark: Array speed - MeasureThat.net

Script Preparation code:

var toStr = Object.prototype.toString
	
function toStrCase(obj){
  return toStr.call(obj) === '[object Array]'
}
function consCase(obj){
  return obj.constructor === Array
}
function instCase(obj){
  return obj instanceof Array
}
var isArray = Array.isArray

Tests:

isArray([])
isArray([])
instCase([])
instCase([])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
isArray([])
instCase([])

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; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36 Zaap3.6.8

Browser/OS: Chrome 123 on Windows

View result in a separate tab

Test name	Executions per second
isArray([])	18665054.0 Ops/sec
instCase([])	6933728.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

The provided JSON represents a benchmark on measuring the speed of checking if an object is an array in different ways. The script preparation code shows three functions that are used to check if an object is an array: `toStrCase`, `consCase`, and `instCase`. These functions use different approaches to determine if an object is an array.

**Options compared:**

1. **`Array.isArray()`**: This method is a built-in JavaScript function that returns a boolean indicating whether the given object is an array.
2. **`obj.constructor === Array`**: This approach uses the `constructor` property of the object and compares it to the `Array` constructor. If they match, it's likely an array.
3. **`obj instanceof Array`**: This approach uses the `instanceof` operator to check if the object is an instance of the `Array` class.

**Pros and Cons:**

*   **`Array.isArray()`**:
    *   Pros:
        *   Fastest method
        *   Widely supported by modern browsers
    *   Cons:
        *   May return incorrect results for certain edge cases (e.g., non-array-like objects)
*   **`obj.constructor === Array`**:
    *   Pros:
        *   Portable and works across all JavaScript engines
    *   Cons:
        *   Can be slower due to the constructor lookup process
*   **`obj instanceof Array`**:
    *   Pros:
        *   Fast and efficient
        *   Works well for most cases
    *   Cons:
        *   May not work correctly for certain edge cases (e.g., prototypal inheritance)

Now, let's discuss the libraries used in these benchmarks.

The `Zaap3.6.8` mentioned in the latest benchmark result is likely a JavaScript engine or interpreter that provides a unique identifier (the "User Agent String") when executed. This string is often used for identifying the browser and its version, as well as other metadata about the execution environment.

There are no specific libraries mentioned in the provided JSON, but it's possible that they might be implied through the use of certain syntax or features.

The `instanceof` operator (`obj instanceof Array`) is a built-in JavaScript operator used to check if an object is an instance of a particular constructor function. This operator is supported by most modern browsers and is often used for type checking in JavaScript.

There are other alternatives to these approaches, such as:

*   **Using a library like Lodash**: Lodash provides a `isArray()` method that can be used for checking if an object is an array.
*   **Implementing custom checks**: Depending on the specific requirements of your project, you might need to implement custom checks for arrays. This could involve using bitwise operations or other techniques.
*   **Using TypeScript or Flow**: If you're working with a statically typed language like TypeScript or Flow, you can use type annotations to ensure that your code is correctly checking if an object is an array.

Overall, the choice of approach depends on the specific requirements and constraints of your project. By understanding the pros and cons of different methods, you can make informed decisions about which one to use.

Related benchmarks:

Array speed (version: 0)

Comparing performance of: isArray([]) vs instCase([])

Created: 2 years ago by: Guest

Jump to the latest result

isArray([])

instCase([])

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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