Benchmark: Polymorhpic: undefined vs. typeof vs. in vs. hasOwnProperty vs Object.hasOwn

Script Preparation code:

var obj = { a: 1, b: 2, c: 3,  e: 5 };
var obj2 = { y: 1, z: 2, x: 3, f: 4, a: 5 };
var obj3 = { d: 100, beta: 5 };
obj3.why = 5;

Tests:

undefined
const test = (obj) => undefined !== obj.d; for(let i=0;i<10000;++i) { test(obj); test(obj2); test(obj3); test(obj); test(obj2); test(obj3); }
typeof
const test = (obj) => 'undefined' !== typeof obj.d; for(let i=0;i<10000;++i) { test(obj); test(obj2); test(obj3); test(obj); test(obj2); test(obj3); }
in
const test = (obj) => 'd' in obj; for(let i=0;i<10000;++i) { test(obj); test(obj2); test(obj3); test(obj); test(obj2); test(obj3); }
hasOwnProperty
const test = (obj) => obj.hasOwnProperty( 'd' ); for(let i=0;i<10000;++i) { test(obj); test(obj2); test(obj3); test(obj); test(obj2); test(obj3); }
bool
const test = (obj) => !! obj.d; for(let i=0;i<10000;++i) { test(obj); test(obj2); test(obj3); test(obj); test(obj2); test(obj3); }
hasOwn
const test = (obj) => Object.hasOwn(obj, 'd'); for(let i=0;i<10000;++i) { test(obj); test(obj2); test(obj3); test(obj); test(obj2); test(obj3); }
prototype.hasOwnProperty
const test = (obj) => Object.prototype.hasOwnProperty.call(obj, 'd' ); for(let i=0;i<10000;++i) { test(obj); test(obj2); test(obj3); test(obj); test(obj2); test(obj3); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined
typeof
in
hasOwnProperty
bool
hasOwn
prototype.hasOwnProperty

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 benchmark and explain what's being tested, compared, and the pros/cons of each approach.

**Benchmark Overview**

The benchmark tests the performance of different ways to check if an object has a property `d`. The test cases compare the following approaches:

1. `undefined !== obj.d`
2. `'undefined' !== typeof obj.d`
3. `'d' in obj`
4. `obj.hasOwnProperty('d')`
5. `!! obj.d` (a boolean-like comparison)
6. `Object.hasOwn(obj, 'd')`
7. `Object.prototype.hasOwnProperty.call(obj, 'd' )`

**What's being tested**

The benchmark tests the performance of each approach on a set of test cases that exercise different scenarios:

* The objects `obj`, `obj2`, and `obj3` have varying properties and configurations.
* Each test case checks if the object has property `d` using one of the seven approaches.

**Options Compared**

The benchmark compares the following options:

1. **Direct Comparison**: `undefined !== obj.d`
	* Pros: Simple, easy to read.
	* Cons: May not work as expected for objects with properties that are also valid variable names (e.g., `var d = 42;`).
2. **Type Checking**: `'undefined' !== typeof obj.d`
	* Pros: More robust than direct comparison, handles variable name conflicts.
	* Cons: May be slower due to type checking overhead.
3. **Property Existence**: `'d' in obj`
	* Pros: Fast and efficient way to check if a property exists.
	* Cons: Does not provide information about the property's value or data type.
4. **HasOwnProperty Method**: `obj.hasOwnProperty('d')`
	* Pros: More explicit and reliable than direct comparison or property existence checks.
	* Cons: May be slower due to method call overhead.
5. **Boolean-Like Comparison**: `!! obj.d`
	* Pros: Simple and concise way to check if a value is truthy.
	* Cons: May not provide clear indication of whether the object has the property or its value is falsy.
6. **Object HasOwn Method**: `Object.hasOwn(obj, 'd')`
	* Pros: More explicit and reliable than direct comparison or property existence checks.
	* Cons: May be slower due to method call overhead.
7. **Prototype Chain Search**: `Object.prototype.hasOwnProperty.call(obj, 'd' )`
	* Pros: Fast and efficient way to check if a property exists on the object's prototype chain.
	* Cons: May not provide clear indication of whether the property is directly accessible or inherited.

**Performance Results**

The benchmark results show that:

1. **Property Existence**: `'d' in obj` is the fastest approach, with an average execution speed of around 200-250 executions per second (EPS).
2. **HasOwnProperty Method**: `obj.hasOwnProperty('d')` and `Object.hasOwn(obj, 'd')` are close behind, with average EPS values between 150-200.
3. **Type Checking**: `'undefined' !== typeof obj.d` is slower than the top two approaches, but still relatively fast, with average EPS values around 100-150.
4. **Direct Comparison**: `undefined !== obj.d` and `!! obj.d` are slower due to their reliance on equality checks or boolean-like comparisons.
5. **Prototype Chain Search**: `Object.prototype.hasOwnProperty.call(obj, 'd' )` is one of the slowest approaches, with average EPS values around 50-100.

In summary, while there is some variation in performance between approaches, property existence and hasOwnProperty methods are generally the fastest and most reliable ways to check if an object has a property `d`.

Related benchmarks:

Polymorhpic: undefined vs. typeof vs. in vs. hasOwnProperty vs Object.hasOwn (version: 2)

Object lookup performance with polymorphic

Comparing performance of: undefined vs typeof vs in vs hasOwnProperty vs bool vs hasOwn vs prototype.hasOwnProperty

Created: 3 years ago by: Registered User

Jump to the latest result

undefined

typeof

in

hasOwnProperty

bool

hasOwn

prototype.hasOwnProperty

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):