Benchmark: zzHasOwn2 - MeasureThat.net

Script Preparation code:

var obj = { a: 1, b: 2, d: 123 };

Tests:

undefined
undefined !== obj.d;
typeof
'undefined' !== typeof obj.d;
in
'd' in obj;
hasOwn
Object.hasOwn(obj, 'd');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined
typeof
in
hasOwn

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 the provided benchmark definition and test cases.

**Benchmark Definition**

The benchmark is designed to measure object lookup performance. The script preparation code creates an object `obj` with properties `a`, `b`, and `d`. The objective is to compare different ways of checking if a property exists in this object.

**Options Compared**

There are four options being compared:

1. **`undefined !== obj.d;`**: This checks if the value of `obj.d` is not equal to `undefined`.
2. **`'undefined' !== typeof obj.d;`**: This checks if the type of `obj.d` (i.e., its string representation) is not equal to `'undefined'`. Note that this uses the `typeof` operator, which returns a string indicating the type of the variable.
3. **`'d' in obj;`**: This uses the `in` operator to check if the property `'d'` exists in the object `obj`.
4. **`Object.hasOwn(obj, 'd');`**: This uses the `hasOwn` method of the `Object` prototype to check if the property `'d'` is an own property of the object `obj`.

**Pros and Cons**

1. **`undefined !== obj.d;`**:
	* Pros: Simple and efficient, as it only checks for equality with `undefined`.
	* Cons: May not work correctly for non-boolean values that are considered "falsey" in a boolean context (e.g., 0, null, undefined).
2. **`'undefined' !== typeof obj.d;`**:
	* Pros: Works for all types of variables, including those with custom string representations.
	* Cons: May be slower due to the overhead of the `typeof` operator and converting the value to a string.
3. **`'d' in obj;`**:
	* Pros: Simple and efficient, as it only checks for existence without comparing values.
	* Cons: May not work correctly if the property name is not a string or if there are multiple properties with the same name (e.g., object literals).
4. **`Object.hasOwn(obj, 'd');`**:
	* Pros: Works correctly even when the property name is not a string or if there are multiple properties with the same name.
	* Cons: May be slower due to the overhead of calling a method on the `Object` prototype.

**Library and Special JS Features**

The only library used in this benchmark is the `Object` prototype, which provides methods like `hasOwn`.

There are no special JavaScript features or syntax used in this benchmark.

**Other Alternatives**

Some alternative ways to check if a property exists in an object might include:

* Using `in` with a regex: `if (obj['d'] && /^x$/.test(obj['d']))`
* Using a library like Lodash's `has`

However, the most straightforward and efficient way is likely to use one of the options listed above (`undefined !== obj.d;`, `'undefined' !== typeof obj.d;`, `in`, or `Object.hasOwn`), depending on the specific requirements and performance considerations.

Related benchmarks:

zzHasOwn2 (version: 0)

Object lookup performance

Comparing performance of: undefined vs typeof vs in vs hasOwn

Created: 3 years ago by: Guest

Jump to the latest result

undefined

typeof

in

hasOwn

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):