Benchmark: Map vs Object hasOwnProperty

Script Preparation code:

var map = new Map();
var obj = {};

map.set('a', 5);
obj['a'] = 5;

var i = 0, count = 1000, a;

Tests:

Map lookup
for (i = 0; i < count; i++) { a = map.get('a'); }
Obj lookup
for (i = 0; i < count; i++) { a = 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: one month ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36

Browser/OS: Chrome 145 on Linux

View result in a separate tab

Test name	Executions per second
Map lookup	7607.0 Ops/sec
Obj lookup	7545.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided JSON benchmark definition and test cases.

**Benchmark Definition Overview**

The provided JSON represents a JavaScript microbenchmark that compares two different approaches for performing a lookup operation on an object: using the `hasOwnProperty` method on an object, and using the `get` method on a Map data structure.

**Options Compared**

Two options are compared:

1. **Object Lookup (`obj.hasOwnProperty('a')`)**: This approach uses the `hasOwnProperty` method on an object to check if a property exists with a given key.
2. **Map Lookup (`map.get('a')`)**: This approach uses the `get` method on a Map data structure to retrieve the value associated with a specific key.

**Pros and Cons of Each Approach**

* **Object Lookup (`obj.hasOwnProperty('a')`)**
	+ Pros:
		- Widely supported across different browsers and JavaScript engines.
		- Generally faster than using `map.get()` because it only checks if the property exists, rather than retrieving its value.
	+ Cons:
		- May be slower for large datasets due to the overhead of iterating through object properties.
		- Less efficient than `map.get()` when working with large datasets or performance-critical code paths.
* **Map Lookup (`map.get('a')`)**
	+ Pros:
		- More efficient than object lookup, especially for large datasets, because it uses a hash table data structure to store and retrieve values quickly.
		- Can be faster than object lookup for small to medium-sized datasets or performance-critical code paths.
	+ Cons:
		- Less widely supported across different browsers and JavaScript engines (although most modern browsers support Maps).
		- May be slower for very large datasets due to the overhead of creating and maintaining a hash table.

**Library and Purpose**

In this benchmark, the `Map` data structure is used. A Map is a built-in JavaScript data structure that stores key-value pairs in an ordered collection. It provides efficient lookup, insertion, and deletion operations, making it suitable for applications where fast lookups are required.

**Special JS Feature or Syntax (None)**

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

**Alternative Approaches**

Other approaches to perform a lookup operation on an object or Map data structure include:

* Using the `in` operator: `obj['a'] in obj || map['a'] in map`
* Using the `==` operator with the `Object.keys()` method: `obj['a'] == Object.keys(obj).length - 1`
* Using a library like Lodash's `_.has()` function: `_.has(obj, 'a')`

Note that these alternative approaches may have different performance characteristics and are not necessarily better or worse than the options compared in this benchmark.

Related benchmarks:

Map vs Object hasOwnProperty (version: 0)

Lookup of map vs object

Comparing performance of: Map lookup vs Obj lookup

Created: 4 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):