Benchmark: isIteratorOrAsyncIterator

HTML Preparation code:

var a = (function *() {})();
var b = undefined;
var c = null;
var d = {next: () => ({value: 1, done: false})};

Script Preparation code:

var a = (function *() {})();
var b = undefined;
var c = null;
var d = {next: () => ({value: 1, done: false})};
var values = [a, b, c, d];

Tests:

null check with next typeof check
for (const value of values) { if (value != null && typeof value.next === "function") { } }
boolean check with next typeof check
for (const value of values) { if (value && typeof value.next === "function") { } }
boolean check with next boolean check
for (const value of values) { if (value && value.next) { } }
null or undefined with next typeof check
for (const value of values) { if (value !== undefined && value !== null && typeof value.next === "function") { } }
null or undefined with boolean next check
for (const value of values) { if (value !== undefined && value !== null && value.next) { } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
null check with next typeof check
boolean check with next typeof check
boolean check with next boolean check
null or undefined with next typeof check
null or undefined with boolean next check

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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 JSON and its associated test cases.

**Benchmark Definition:**

The benchmark measures the performance of JavaScript code that checks for the existence and type of a `next` property on various objects, including arrays, null, and undefined values. The script preparation code sets up an array of four objects: `a`, `b`, `c`, and `d`, where `d` is an object with a `next` method.

**Options being compared:**

The benchmark tests four different ways to check for the existence and type of a `next` property:

1. **Null check with next typeof check**: Checks if the object is not null and has a function type for its `next` property.
2. **Boolean check with next typeof check**: Checks if the object is truthy (i.e., not null or undefined) and has a function type for its `next` property.
3. **Boolean check with next boolean check**: Checks if the object is truthy (i.e., not null or undefined) and has a non-null value for its `next` property.
4. **Null or undefined with next typeof check**: Checks if the object is neither null nor undefined and has a function type for its `next` property.
5. **Null or undefined with boolean next check**: Checks if the object is neither null nor undefined and has a non-null value for its `next` property.

**Pros and cons of each approach:**

1. **Null check with next typeof check**: This approach is straightforward but may lead to false positives if the object is not an array, as `typeof` returns `function` for any function.
2. **Boolean check with next typeof check**: This approach is more robust than the null check but may still produce false positives for non-array objects.
3. **Boolean check with next boolean check**: This approach is more specific to arrays and may be faster since it only checks if the object has a `next` property, regardless of its type.
4. **Null or undefined with next typeof check**: This approach ensures that the object is not null or undefined before checking the `next` property, making it more robust than the boolean checks.
5. **Null or undefined with boolean next check**: This approach is similar to the previous one but also considers the value of the `next` property.

**Libraries and special JS features:**

None of the test cases use any external libraries. However, they do utilize some JavaScript syntax:

* Arrow functions (`() => ...`) are used to define small anonymous functions.
* Template literals (`\r\n...`) are used to concatenate strings with newline characters.
* The `typeof` operator is used to check the type of a variable.

**Alternative approaches:**

Other alternatives for checking if an object has a `next` property include:

* Using the `instanceof` operator, which checks if an object is an instance of a specific class (e.g., `Array.prototype`).
* Using the `hasOwnProperty` method, which returns true if the object has the specified property.
* Using a library like Lodash's `isArray` function or a custom implementation using the `Object.prototype.hasOwnProperty.call` method.

These alternatives may offer different trade-offs in terms of performance, readability, and robustness.

Related benchmarks:

isIteratorOrAsyncIterator (version: 0)

Comparing performance of: null check with next typeof check vs boolean check with next typeof check vs boolean check with next boolean check vs null or undefined with next typeof check vs null or undefined with boolean next check

Created: 5 years ago by: Guest

Jump to the latest result

null check with next typeof check

boolean check with next typeof check

boolean check with next boolean check

null or undefined with next typeof check

null or undefined with boolean next 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):