Benchmark: Null VS Undefined

Tests:

Null
for (let i = 0; i < 50000; ++i) { let val = null; val = 10; }
Undefined
for (let i = 0; i < 50000; ++i) { let val = undefined; val = 10; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Null
Undefined

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 months ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:142.0) Gecko/20100101 Firefox/142.0

Browser/OS: Firefox 142 on Ubuntu

View result in a separate tab

Test name	Executions per second
Null	22432.5 Ops/sec
Undefined	20859.8 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, compared, and analyzed.

**What is being tested?**

The benchmark is testing two different values in JavaScript: `null` (a special value that represents the absence of any object value) and `undefined` (a special value that represents an uninitialized variable or a property that has not been assigned a value).

**Options compared:**

Two options are being compared:

1. **Null**: The benchmark uses `let val = null;` to assign `null` to a variable `val`. This means that the `val` variable is intentionally initialized with `null`.
2. **Undefined**: The benchmark uses `let val = undefined;` to assign `undefined` to a variable `val`. This means that the `val` variable is intentionally uninitialized.

**Pros and Cons:**

*   **Null**: Using `null` as an initialization value can be beneficial in certain scenarios, such as when working with APIs or data formats that expect null values. However, it's generally considered better practice to initialize variables with a more explicit value (e.g., 0) rather than relying on the default value of null.
*   **Undefined**: Initializing a variable with `undefined` can be problematic, as it may lead to unexpected behavior in certain situations. In general, it's recommended to avoid initializing variables with `undefined`.

**Other considerations:**

When working with JavaScript, it's essential to consider how different initialization values affect the overall behavior of your code.

*   **Type Coercion**: In JavaScript, the `===` operator checks for both value and type equality. When comparing a variable initialized with `null` or `undefined`, the comparison may not behave as expected due to type coercion rules.
*   **Nullish Coalescing Operator (`??`)**: This operator was introduced in ECMAScript 2020, allowing developers to provide a default value that is more suitable for null or undefined values. Using this operator can help simplify code and improve readability.

**Library and syntax:**

No libraries are used in the provided benchmark definition. However, if you're interested in exploring JavaScript libraries, some popular ones include:

*   **Lodash**: A comprehensive utility library providing various functions for working with arrays, objects, and more.
*   **Moment.js**: A popular date formatting library that can help simplify date-related calculations.

**Special JS feature or syntax:**

The provided benchmark does not use any special JavaScript features or syntax, such as async/await, generators, or decorators.

**Alternatives:**

If you'd like to explore alternative approaches for creating and running microbenchmarks in JavaScript, consider the following options:

*   **Benchmark.js**: A lightweight library providing a simple API for creating and running benchmarks.
*   **Jest**: A popular testing framework that includes built-in benchmarking capabilities.

These alternatives can help simplify your workflow and provide additional features for creating high-quality benchmarks.

Related benchmarks:

Null VS Undefined (version: 0)

Comparing performance of: Null vs Undefined

Created: 6 years ago by: Guest

Jump to the latest result

Null

Undefined

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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