Benchmark: big object undefined vs. typeof vs. in vs. hasOwnProperty

Script Preparation code:

var obj = {};
for (let i = 0; i < 1000000; i++) {
    const randomStr = Math.random().toString(36) + Math.random().toString(36);
    obj[randomStr] = randomStr;
}

Tests:

undefined
undefined !== obj.d;
typeof
'undefined' !== typeof obj.d;
in
'd' in obj;
hasOwnProperty
obj.hasOwnProperty( 'd' );
bool
!! obj.d;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined
typeof
in
hasOwnProperty
bool

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Definition JSON**

The provided benchmark definition represents an object lookup performance comparison between different approaches in JavaScript.

* `Script Preparation Code`: This code creates a large object (`obj`) with 1 million properties, where each property is a random string. The purpose of this code is to generate a large, dense data structure that will be used for object lookups.
* `Html Preparation Code`: Since there is no HTML preparation code, it implies that the test only runs in a JavaScript environment (e.g., Node.js or a web browser).

**Individual Test Cases**

The benchmark consists of five individual test cases:

1. `undefined !== obj.d;`
2. `'undefined' !== typeof obj.d;`
3. `'d' in obj;`
4. `obj.hasOwnProperty('d');`
5. `!! obj.d;`

These test cases aim to evaluate the performance of different approaches for object lookups.

**Options Compared**

The options compared are:

* `undefined` vs. `typeof` (test case 1)
* `typeof` vs. `in` (test case 2)
* `in` vs. `hasOwnProperty` (test case 3)
* `hasOwnProperty` vs. `!! obj.d` (test case 4)
* `!! obj.d` vs. none of the above (test case 5)

**Pros and Cons of Each Approach**

Here's a brief analysis of each approach:

1. **`undefined`**: This is not a standard JavaScript way to check if a property exists in an object. It's more of a hack, as `obj.d` will return `undefined` because it doesn't exist.
	* Pros: None
	* Cons: Insecure, non-standard
2. **`typeof`**: This checks the type of the value associated with the property using the `typeof` operator.
	* Pros: Widespread support and clarity
	* Cons: May not work for objects or functions (returns 'object' or 'function')
3. **`in`**: This checks if a property exists in an object using the `in` operator.
	* Pros: Works with objects, functions, and symbols
	* Cons: May return true for properties that don't exist (e.g., inherited properties)
4. **`hasOwnProperty`**: This method is specific to the `Object.prototype` object and checks if a property exists only in the current object.
	* Pros: Specificity and performance
	* Cons: Limited support, requires `Object.prototype`
5. **`!! obj.d` (test case 5)**: This uses the logical NOT operator (`!!`) to check if the value associated with `obj.d` is falsy (i.e., null or undefined).
	* Pros: Clarity and simplicity
	* Cons: May not work for objects that contain non-falsy values

**Library**

None of these test cases rely on a specific library. However, it's worth noting that the `hasOwnProperty` method is part of the `Object.prototype`, which is inherited by all objects in JavaScript.

**Special JS Feature or Syntax**

This benchmark doesn't explicitly use any special features or syntax, but it does rely on the `typeof` operator, which is a standard feature in JavaScript. The `in` operator and `hasOwnProperty` method also work with modern JavaScript environments.

Now that we've explored the benchmark, let's discuss alternatives:

**Alternatives**

If you want to explore alternative approaches for object lookups, consider the following options:

* Use the `Object.hasOwn()` method (available in ECMAScript 2015+), which provides a more specific and secure way to check if an object has a property.
* Utilize the `Symbol` data type, which can be used with the `in` operator for more precise and modern lookups.
* Experiment with other methods like `Object.keys()` or `Object.values()`, which provide alternative ways to access properties.

Keep in mind that performance optimization should always consider the specific use case and requirements of your application.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.110 Safari/537.36

Browser/OS: Chrome 96 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
undefined	9182757.0 Ops/sec
typeof	24382280.0 Ops/sec
in	23320154.0 Ops/sec
hasOwnProperty	19446808.0 Ops/sec
bool	24366938.0 Ops/sec

Related benchmarks:

big object undefined vs. typeof vs. in vs. hasOwnProperty (version: 0)

Object lookup performance

Comparing performance of: undefined vs typeof vs in vs hasOwnProperty vs bool

Created: 2 years ago by: Guest

Jump to the latest result

undefined

typeof

in

hasOwnProperty

bool

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):