Benchmark: lodash isUndefined vs typeof === undefined (take 3)

HTML Preparation code:

<script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js'></script>

Script Preparation code:

var foo;

Tests:

lodash.isUndefined
if (_.isUndefined(foo)) { foo; }
triple equals
if (foo === undefined) { foo; }
typeof
if (typeof foo === 'undefined') { foo; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
lodash.isUndefined
triple equals
typeof

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36

Browser/OS: Chrome 145 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
lodash.isUndefined	157868432.0 Ops/sec
triple equals	157023296.0 Ops/sec
typeof	151629472.0 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.

**Benchmark Overview**

The provided benchmark tests three ways to check if a variable is undefined: using `_.isUndefined` from the Lodash library, the triple equals operator (`===`), and the `typeof` operator with `'undefined'`.

**Lodash.isUndefined**

* **Purpose**: The `_.isUndefined` function checks if a value is `undefined`, `null`, or `NaN`.
* **Library**: Lodash (a popular utility library for JavaScript) provides this function.
* **Pros**: This approach can be more concise and expressive, as it uses a dedicated function to perform the check. However, it may introduce additional overhead due to the need to import the Lodash library.
* **Cons**: It's only available in browsers that support ES6 imports or in environments where the library is explicitly loaded.

**Triple Equals (`===`)**

* **Purpose**: This operator checks if two values are equal and of the same type (i.e., both `undefined`, both numbers, etc.).
* **Pros**: This approach is lightweight and doesn't require any additional libraries.
* **Cons**: It may be less readable or more prone to errors in some cases (e.g., comparing a number with `undefined`).

**typeof**

* **Purpose**: The `typeof` operator returns a string describing the type of a value, including whether it's `undefined`.
* **Pros**: This approach is built-in and widely supported across browsers. It can also be used to check for other types (e.g., `number`, `string`, etc.).
* **Cons**: It may not provide the exact same behavior as `_.isUndefined` in all cases, and it's more verbose.

**Comparison Summary**

| Approach | Pros | Cons |
| --- | --- | --- |
| Lodash.isUndefined | Concise, expressive | Adds library overhead |
| Triple Equals (`===`) | Lightweight | Less readable or prone to errors |
| typeof | Built-in, widely supported | May not match Lodash behavior |

**Other Alternatives**

In addition to these three approaches, other ways to check for undefined values include:

* Using `==` or `===` with a loose equality check (e.g., comparing a value to `undefined` using `==`)
* Using the `in` operator (which returns true if a property is defined on an object)
* Implementing a custom function to perform the check

Keep in mind that these alternatives may have different performance characteristics, readability, or compatibility across browsers.

Related benchmarks:

lodash isUndefined vs typeof === undefined (take 3) (version: 0)

Comparing performance of: lodash.isUndefined vs triple equals vs typeof

Created: 3 years ago by: Guest

Jump to the latest result

lodash.isUndefined

triple equals

typeof

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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