Benchmark: Null check vs typeof

Script Preparation code:

var a = undefined;
if (Math.random() > 0.5) {
  a = 3;
}

Tests:

typeof
typeof a === "number"
null check
a != null

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
typeof
null check

Fastest: N/A

Slowest: N/A

Latest run results:

No previous 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 dive into the world of MeasureThat.net and explore what's being tested in this particular benchmark.

**Benchmark Overview**

The benchmark compares two approaches to check if a variable `a` is not null (or undefined): using the `typeof` operator with an explicit type `"number"` or a simple null check `a != null`.

**Options Compared**

The two options being compared are:

1. **`typeof` with `"number"`**: This approach uses the `typeof` operator to check if the variable `a` is of type "number". If it's not, the expression will be false.
2. **Null Check (`a != null)`**: This approach directly checks if the variable `a` is not null (or undefined).

**Pros and Cons**

**1. `typeof` with `"number"`**:

Pros:

* More explicit and clear in its intent
* May be faster due to optimization by the JavaScript engine

Cons:

* Can lead to unexpected behavior if the variable is not exactly a number, but rather an object or a function that returns a number.
* May require additional type checks or assertions to ensure correctness.

**2. Null Check (`a != null)`**

Pros:

* More straightforward and intuitive
* Does not rely on explicit type checking or parsing

Cons:

* May be slower due to the need for a separate check.

**Other Considerations**

In this benchmark, it's worth noting that `typeof` has a special case for "number" types in JavaScript engines. This might affect the performance difference between the two approaches.

Additionally, the use of `Math.random()` to conditionally set `a` introduces some randomness in the benchmark, which can make it more challenging to determine the true performance differences between the two approaches.

**Library and Special JS Feature**

There are no libraries being used in this benchmark. However, the use of `typeof` operator and null checks relies on JavaScript's built-in syntax and features.

If you're interested in exploring other alternatives or optimizations, some possible options include:

* Using a different type system or library (e.g., TypeScript) that provides stronger type checking.
* Utilizing advanced optimization techniques specific to Chrome 89, such as `Array.prototype.slice()` or `Function.prototype.call()`.
* Investigating the impact of different platform-specific optimizations or heuristics on performance.

Keep in mind that MeasureThat.net is primarily focused on comparing JavaScript engine behaviors and performance characteristics. If you're interested in exploring alternative options or optimizations, I recommend checking out other resources or benchmarking platforms specifically designed for exploring such topics.

Related benchmarks:

Null check vs typeof (version: 0)

Comparing performance of: typeof vs null check

Created: 5 years ago by: Guest

Jump to the latest result

typeof

null check

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):