Benchmark: Test speed of undefined

Script Preparation code:

var test = undefined;

Tests:

Check for the real variable.
test === 2;
Check for the opposite.
test !== 2;
Check for another variable.
test !== undefined;
Check for another variable without comparisson.
test;
Check for another variable denying it..
!test;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Check for the real variable.
Check for the opposite.
Check for another variable.
Check for another variable without comparisson.
Check for another variable denying it..

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.86 Safari/537.36

Browser/OS: Chrome 89 on Windows

View result in a separate tab

Test name	Executions per second
Check for the real variable.	7585689.5 Ops/sec
Check for the opposite.	7501893.0 Ops/sec
Check for another variable.	2828689.2 Ops/sec
Check for another variable without comparisson.	7158975.5 Ops/sec
Check for another variable denying it..	7628250.0 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 JSON and benchmark information to understand what is being tested.

**Benchmark Overview**

The website `MeasureThat.net` allows users to create and run JavaScript microbenchmarks. The current benchmark tests different scenarios related to variable checks in JavaScript, specifically focusing on the behavior of the unary operator "!" (not) with its operands.

**Script Preparation Code**

The script preparation code is: `"var test = undefined;"`. This line declares a new variable `test` and assigns it an undefined value. The purpose of this setup is to create a scenario where the benchmark can measure the performance of various conditional checks.

**Benchmark Definition JSON**

The provided JSON contains five individual benchmark definitions, each representing a different test case:

1. `test === 2;`
2. `test !== 2;`
3. `test !== undefined;`
4. `test;` (no comparison)
5. `!test;`

These test cases cover various scenarios:

*   A simple equality check (`test === 2;`)
*   An inequality check with a literal value (`test !== 2;`)
*   Checking for the existence of another variable (`test !== undefined;`)
*   Accessing a variable without any comparison (`test;`)
*   Negating the result of a variable access (`!test;`)

**Comparison Options and Their Pros/Cons**

Here's an overview of each test case:

1.  **Equality check**: `test === 2;`
    *   **Pros:** Directly compares two values, providing clear results.
    *   **Cons:** Requires the variable to be defined with a specific value.
2.  **Inequality check with literal**: `test !== 2;`
    *   **Pros:** Fast and straightforward for simple cases.
    *   **Cons:** May not provide accurate results if the variable has side effects or takes time to resolve.
3.  **Existence check**: `test !== undefined;`
    *   **Pros:** Can be useful when determining whether a variable exists, especially in null-conditional checks.
    *   **Cons:** May incur performance overhead due to the comparison and potential null checks.
4.  **Direct access without comparison**: `test;`
    *   **Pros:** Can provide insight into memory access patterns or specific optimizations within the JavaScript engine.
    *   **Cons:** Provides limited useful information and may not be representative of real-world usage scenarios.

**Library Usage**

There is no explicit library mentioned in the provided JSON. However, MeasureThat.net likely utilizes a combination of browser-specific APIs (e.g., `performance.now()` or `PerformanceObserver`) to measure execution times.

**Special JS Features/Syntax**

The benchmark does not explicitly use any special JavaScript features or syntax, such as async/await, closures, or specific modules like ES6 modules.

**Alternatives**

Some alternatives for building microbenchmarks in JavaScript include:

*   **jsperf**: A deprecated but still supported benchmarking library.
*   **Benchmark.js**: Another widely used and actively maintained benchmarking library.
*   **WebAssembly-based benchmarks**: For more complex, low-level optimizations or performance comparisons.

When choosing a benchmarking library, consider factors such as ease of use, scalability, and platform support to ensure your test suite is effective and representative.

Related benchmarks:

Test speed of undefined (version: 0)

Test speed of !== undefined vs. only the variable name.

Comparing performance of: Check for the real variable. vs Check for the opposite. vs Check for another variable. vs Check for another variable without comparisson. vs Check for another variable denying it..

Created: 3 years ago by: Guest

Jump to the latest result

Check for the real variable.

Check for the opposite.

Check for another variable.

Check for another variable without comparisson.

Check for another variable denying it..

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):