Benchmark: value vs typeof - MeasureThat.net

Script Preparation code:

var myVar = undefined;

Tests:

value
myVar === undefined;
typeof
typeof myVar === 'undefined';

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
value
typeof

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON data to understand what is being tested in this JavaScript microbenchmark.

**Benchmark Definition**

The benchmark definition represents the core logic of the test case. In this case, there are two test cases:

1. `myVar === undefined;` (Test Case 1: "value")
2. `typeof myVar === 'undefined';` (Test Case 2: "typeof")

These two expressions aim to check if a variable `myVar` is equal to `undefined`. The difference lies in how they achieve this.

**Options Compared**

Two approaches are being compared:

A) Using the `===` operator for equality comparison (`value`).
B) Using the `typeof` operator with a string literal `'undefined'` for type checking (`typeof`).

**Pros and Cons of Each Approach:**

1. **Using `===` Operator (Value):**
	* Pros:
		+ Fastest way to check for exact value equality.
		+ Less CPU-intensive than `typeof`.
	* Cons:
		+ Less readable or intuitive, as it's not a standard way of checking if a variable is undefined.
2. **Using `typeof` Operator with `'undefined'` (Type):**
	* Pros:
		+ More readable and intuitive, as it clearly conveys the intention of checking for type.
		+ Widely supported across different browsers and environments.
	* Cons:
		+ Less performant than `===`, as it involves a function call and potential type conversions.

**Library Usage**

In this benchmark, no external libraries are explicitly mentioned. However, `typeof` is a built-in JavaScript operator that relies on the browser's or environment's implementation of the ECMAScript standard.

**Special JS Feature/Syntax**

There is no special JS feature or syntax used in this benchmark. The expressions rely solely on standard JavaScript language constructs.

**Other Alternatives**

For this specific use case, other alternatives to `===` and `typeof` could be considered:

* `==` (loose equality operator): While not recommended due to its imprecision, it might provide a slight performance boost for simple cases.
* `Object.prototype.toString.call(myVar)` or `myVar.toString()` (type checking using the `toString()` method): These approaches are more explicit and readable but can be slower than `typeof`.
* Using a library like `lodash` or `is-undefined`: These libraries provide optimized implementations of these operators, which might offer better performance and readability.

Keep in mind that the choice of approach often depends on the specific use case, personal preference, and the desired balance between readability, performance, and compatibility.

Related benchmarks:

value vs typeof (version: 0)

value vs typeof

Comparing performance of: value vs typeof

Created: 3 years ago by: Registered User

Jump to the latest result

value

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):