Benchmark: Short undef check

Script Preparation code:

var obj = { a: new Set() }

function hasA(obj) {
  return ('a' in obj);
}

function hasB(obj) {
  return ('b' in obj);
}

function hasC(obj) {
  return ('c' in obj);
}

Tests:

?
const a = obj.a?.has(42) const b = obj.b?.has(42) const c = obj.c?.has(42)
basic
const a = obj.a && obj.a.has(42) const b = obj.b && obj.b.has(42) const c = obj.c && obj.c.has(42)
in
const a = ('a' in obj) && obj.a.has(42) const b = ('b' in obj) && obj.b.has(42) const c = ('c' in obj) && obj.c.has(42)
!== undefined
const a = obj.a !== undefined && obj.a.has(42) const b = obj.b !== undefined && obj.b.has(42) const c = obj.c !== undefined && obj.c.has(42)
function check
const a = hasA(obj) && obj.a.has(42) const b = hasB(obj) && obj.b.has(42) const c = hasC(obj) && obj.c.has(42)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
?
basic
in
!== undefined
function 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 break down what is being tested in the provided JSON benchmark.

**Benchmark Definition**

The script preparation code defines two functions: `hasA`, `hasB`, and `hasC`. These functions check if certain properties (`a`, `b`, and `c`) exist in an object. The comparison operator used is either `in` (for the `in` test case), or a combination of an assignment operator (`=`) with a conditional statement.

**Options being compared**

1. **Direct property access**: `obj.a.has(42)` (tested in "hasA" function)
	* Pros: Simple and efficient way to check if a property exists.
	* Cons: May be slower than other methods due to the need for an additional call to `has()`.
2. **Using `in` operator**: `('a' in obj) && obj.a.has(42)` (tested in "in" test case)
	* Pros: More flexible way to check if a property exists, works even if `obj` is null or undefined.
	* Cons: May be slower than direct property access due to the need for the `in` operator.
3. **Using conditional assignment**: `obj.a = true; obj.a.has(42)` (not tested in this benchmark)
	* Pros: Works even if `obj` is null or undefined, avoids the need for an additional call to `has()`.
	* Cons: May be slower than direct property access due to the need for an assignment.
4. **Using a separate function**: `hasA(obj) && obj.a.has(42)` (tested in "function check" test case)
	* Pros: More readable and maintainable way to check if a property exists, avoids code duplication.

**Library**

The benchmark uses the `Set` data structure, which is implemented by JavaScript. A `Set` is an object that stores unique values and allows for efficient membership testing using the `has()` method.

**Special JS feature or syntax**

This benchmark does not use any special JavaScript features or syntax beyond what's considered standard (ECMAScript 2022). However, it does rely on the `&&` operator to combine conditional statements, which is a standard part of JavaScript syntax.

**Other considerations**

The benchmark measures the execution speed of each test case across multiple browsers and devices. The results provide insight into how different approaches to property existence checking perform in various environments.

As for alternatives, other ways to check if a property exists in an object include:

1. Using `obj.hasOwnProperty('a')`
2. Using `Object.prototype.hasOwnProperty.call(obj, 'a')` (not recommended due to potential performance implications)
3. Using a library like Lodash's `has` function
4. Writing a custom implementation using bitwise operations or other techniques.

However, these alternatives are not typically used in production code and may be slower than the methods tested in this benchmark.

Related benchmarks:

Short undef check (version: 0)

Comparing performance of: ? vs basic vs in vs !== undefined vs function check

Created: 3 years ago by: Guest

Jump to the latest result

?

basic

in

!== undefined

function 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):