Benchmark: equals undefined

Script Preparation code:

var values = [];
for (i = 0; i < 1000; i += 1) {
  values[i] = Math.random() < 0.5 ? {a: 5} : {b: 5};
}

Tests:

===
values.filter(a => a.a === undefined)
typeof
values.filter(a => typeof a.a === "undefined")

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
===
typeof

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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 MeasureThat.net and explore what's being tested in this benchmark.

**Benchmark Definition**

The benchmark is defined by two JavaScript functions: `values.filter(a => a.a === undefined)` and `values.filter(a => typeof a.a === "undefined")`. These two functions are compared to measure their performance.

**What is being tested?**

These functions are testing the same condition, but using different approaches:

1. **`a => a.a === undefined`**: This function uses an arrow function with a conditional statement (`===`). It checks if the `a` object has a property `a` that is equal to `undefined`.
2. **`a => typeof a.a === "undefined"`**: This function uses another arrow function, this time using the `typeof` operator to check the type of `a.a`. It returns `true` only if `a.a` is an undefined value.

**Pros and Cons**

Here's a brief analysis of each approach:

1. **Equality Check (`a => a.a === undefined`)**:
	* Pros: Simple, easy to read, and well-established in JavaScript.
	* Cons: May be slower due to the overhead of comparing primitive values using `===`.
2. **Type Checking (`a => typeof a.a === "undefined"`)**:
	* Pros: Can be faster since it only checks the type, not the value itself.
	* Cons: Less readable and may require more maintenance due to potential issues with `typeof` behavior.

**Library Usage**

None of these benchmark functions use any external libraries. The JavaScript code is self-contained and only relies on built-in functionality.

**Special JS Feature or Syntax**

The benchmark uses arrow functions (`a => a.a === undefined`) and the `typeof` operator, which are both modern JavaScript features introduced in ES6+ (EcmaScript 2015). This means that older browsers may not support these features, which could affect the test results.

**Alternatives**

Other alternatives for comparing objects or testing properties include:

1. **Object.prototype.hasOwnProperty.call()**: A more verbose but reliable way to check if a property exists.
2. **Object.keys() and array.includes()**: Can be used to check if an object has a specific property, but may not work as expected if the property is inherited from another object.

In summary, MeasureThat.net is testing two JavaScript functions that compare the same condition using different approaches: equality checks (`===`) vs. type checking (`typeof`). The pros and cons of each approach are discussed, along with considerations for library usage, special features, and alternative methods for comparison.

Related benchmarks:

equals undefined (version: 0)

Comparing performance of: === vs typeof

Created: 5 years ago by: Guest

Jump to the latest result

===

typeof

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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