Benchmark: double equals null vs boolean

Script Preparation code:

var values = [(function*() {})(), undefined, null, {}];

Tests:

== null
let isIterable; for (const value of values) { isIterable = value != null && typeof value[Symbol.iterator] === "function"; }
implicit boolean conversion
let isIterable; for (const value of values) { isIterable = value && typeof value[Symbol.iterator] === "function"; }
explicit boolean conversion
let isIterable; for (const value of values) { isIterable = !!value && typeof value[Symbol.iterator] === "function"; }
typeof + triple equals null
let isIterable; for (const value of values) { isIterable = typeof value !== "undefined" && value !== null && typeof value[Symbol.iterator] === "function"; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
== null
implicit boolean conversion
explicit boolean conversion
typeof + triple equals null

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.

**What is tested:**

The provided JSON represents a JavaScript microbenchmark test case, which compares the performance of three different approaches to check if a value is iterable (i.e., it can be iterated over using a for...of loop). The three approaches are:

1. **Explicit boolean conversion**: Using `!!value` to convert the value to a boolean.
2. **Implicit boolean conversion**: Using `value != null && typeof value[Symbol.iterator] === "function"`.
3. **Type triple equals null**: Using `typeof value !== "undefined" && value !== null && typeof value[Symbol.iterator] === "function"`.

**Options comparison:**

* **Explicit boolean conversion (!!value)**:
	+ Pros: Simple and straightforward.
	+ Cons: May introduce unnecessary type conversions, which can be slower.
* **Implicit boolean conversion (value != null && typeof value[Symbol.iterator] === "function")**:
	+ Pros: Avoids unnecessary type conversions, which can improve performance.
	+ Cons: Requires knowledge of the `!` operator and the `Symbol.iterator` property.
* **Type triple equals null (typeof value !== "undefined" && value !== null && typeof value[Symbol.iterator] === "function")**:
	+ Pros: Provides additional safety checks for non-null values, which can prevent errors in some cases.
	+ Cons: May be slower due to the extra checks and type conversions.

**Library usage:**

None of the benchmark test cases use any external libraries.

**Special JavaScript features or syntax:**

* `Symbol.iterator`: This is a built-in symbol that represents an iterator. It's used to check if a value can be iterated over using a for...of loop.
* `!!value` (explicit boolean conversion): This is a shorthand way of converting a value to a boolean by negating it and then casting it back to a boolean.

**Other alternatives:**

In addition to the three approaches mentioned above, other ways to check if a value is iterable might include:

* Using a try-catch block with `try { for (const _ of value) {} } catch (_) {}`: This approach can be slower than the explicit boolean conversion.
* Using `Array.isArray()` and `typeof value === "object"`: This approach relies on the `Array.isArray()` function, which is not always available in older browsers or environments.

However, these alternatives are generally less efficient and may not be supported by all browsers or environments.

Related benchmarks:

double equals null vs boolean (version: 0)

Comparing performance of: == null vs implicit boolean conversion vs explicit boolean conversion vs typeof + triple equals null

Created: 5 years ago by: Guest

Jump to the latest result

== null

implicit boolean conversion

explicit boolean conversion

typeof + triple equals null

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):