Benchmark: Map has vs Object hasOwnProperty

Script Preparation code:

var map = new Map();
var obj = {};

map.set('a', 5);
obj['a'] = 5;

var i = 0, count = 100000;

Tests:

Map lookup
for (i = 0; i < count; i++) { map.has('a'); }
Obj lookup
for (i = 0; i < count; i++) { obj.hasOwnProperty('a'); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Map lookup
Obj lookup

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:141.0) Gecko/20100101 Firefox/141.0

Browser/OS: Firefox 141 on Linux

View result in a separate tab

Test name	Executions per second
Map lookup	6657.3 Ops/sec
Obj lookup	7238.8 Ops/sec

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 and explain what's being tested, compared, and considered.

**Benchmark Overview**

The benchmark is designed to compare the performance of two different ways to check if a key exists in an object or map:

1. **Map lookup**: Using the `has()` method on a `Map` instance.
2. **Object lookup**: Using the `hasOwnProperty()` method on an object (represented as a plain JavaScript object, not an actual DOM element).

**Options Compared**

The benchmark is comparing two approaches:

* **Map lookup**: Using `map.has('a')`
* **Object lookup**: Using `obj.hasOwnProperty('a')`

These two methods are designed to achieve the same result: checking if a key exists in the map/object. However, they have different implementations and potential performance implications.

**Pros and Cons of Each Approach**

1. **Map Lookup (using `has()` method)**:
	* Pros:
		+ More concise and readable code.
		+ Likely to be implemented as a single, optimized function call.
	* Cons:
		+ May have slower performance due to the additional overhead of checking if the key is present in the map.
2. **Object Lookup (using `hasOwnProperty()` method)**:
	* Pros:
		+ Might be faster due to the optimized implementation of `hasOwnProperty()`.
	* Cons:
		+ Less concise and readable code compared to `map.has('a')`.

**Library Usage**

In this benchmark, a `Map` instance is created using `var map = new Map();`. The purpose of a `Map` is to store key-value pairs and provide fast lookups, insertions, and deletions. In this case, the `has()` method on the map is used to check if a specific key (`'a'`) exists.

**Special JavaScript Feature**

The benchmark uses the **arrow function syntax**, which was introduced in ECMAScript 2015 (ES6). The arrow functions are defined using the `=>` operator and provide a concise way to define small, one-time use functions. In this case, the arrow function is used for simplicity and readability.

**Other Alternatives**

If you were to implement a similar benchmark, other alternatives could include:

* Using the `in` operator instead of `hasOwnProperty()`.
* Implementing a custom lookup function using bitwise operations or hashing.
* Using a different data structure, such as an array with a custom length property, to store key-value pairs.

Keep in mind that these alternatives might introduce additional complexity and potential performance differences.

Related benchmarks:

Map has vs Object hasOwnProperty (version: 0)

Comparing performance of: Map lookup vs Obj lookup

Comparing performance of: Map lookup vs Obj lookup

Created: 3 years ago by: Guest

Jump to the latest result

Map lookup

Obj lookup

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):