Benchmark: Map.has vs Object hasOwnProperty

Script Preparation code:

var map = new Map();
var obj = {};

var j = 0;
while (j < 10000) {
  var key = "Key_" + j;
  map.set(key, 5);
  obj[key] = 5;
  j += 1;
}

var stringKey = 'asdfasdjfa;sjfjaklfjklsjklajjjj;jlsjfajdfsfjs;fjsfka';

var i = 0, count = 1000, a;

Tests:

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

Historical Performance Data aggregated from 7 community runs

Desktop Results:

Chrome 7 runs

Map lookup

9K/s

Obj lookup

9K/s

View exact numbers

✓ Map lookup: 9,433 ops/sec
• Obj lookup: 8,931 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

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 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/149.0.0.0 Safari/537.36

Browser/OS: Chrome 149 on Windows

View result in a separate tab

Map lookup

6K/s

Obj lookup

6K/s

View exact numbers

Test name	Executions per second
✓ Map lookup	6,369 Ops/sec
Obj lookup	5,623 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark and explain what's being tested, the options compared, their pros and cons, and other considerations.

**What's being tested?**

The benchmark tests the performance of two different approaches to check if a key exists in an object: `Map.has()` and `Object.hasOwnProperty()`. The test cases create a large map and object with 10,000 entries each and then look up a specific string key in both data structures.

**Options compared**

There are two options being compared:

1. **`Map.has()`**: This method is used to check if a key exists in a Map object.
2. **`Object.hasOwnProperty()`**: This method is used to check if a property exists in an object using the `hasOwnProperty()` method, which returns true if the object has the specified property as its own property (i.e., not inherited from the prototype chain).

**Pros and Cons**

**`Map.has()`**

Pros:

* Generally faster than `Object.hasOwnProperty()`, especially for large datasets.
* Provides a more efficient way to check if a key exists in a Map, reducing the overhead of searching through the object's properties.

Cons:

* Only available in ECMAScript 2015 (ES6) and later versions.
* Requires the use of a Map object, which may be overkill for simple lookup scenarios.

**`Object.hasOwnProperty()`**

Pros:

* Widely supported across different browsers and environments, including older versions.
* Can be used with any object type, not just Maps.

Cons:

* Slower than `Map.has()`, especially for large datasets.
* May involve searching through the object's prototype chain to find the property, which can lead to slower performance.

**Other considerations**

* The use of a string key in both `Map.has()` and `Object.hasOwnProperty()` may introduce additional overhead due to string processing.
* The test cases create a large dataset (10,000 entries each), which may exaggerate the differences between these two methods. In practice, smaller datasets might not show significant performance differences.

**Library usage**

There is no library explicitly mentioned in the benchmark definition or test cases. However, the use of `Map` and `Object` suggests that the test relies on built-in JavaScript objects.

**Special JS feature/syntax**

None are mentioned in this specific benchmark, but it's worth noting that some newer JavaScript features like `Map.prototype.get()` and `Object.prototype.hasOwnProperty.call()` might be used to optimize these methods further. However, they are not applicable to this particular benchmark definition.

Map.has vs Object hasOwnProperty (version: 0)

Lookup of map vs object

Comparing performance of: `Map lookup vs Obj lookup`

Created: one year ago by: Guest

Go to the latest result

Map lookup

Obj lookup

Historical Performance Data aggregated from 7 community runs

Desktop Results:

Chrome 7 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Map.has vs Object hasOwnProperty (version: 0)

Lookup of map vs object

Comparing performance of: Map lookup vs Obj lookup

Created: one year ago by: Guest

Go to the latest result

Map lookup

Obj lookup

Historical Performance Data aggregated from 7 community runs

Desktop Results:

Chrome 7 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `Map lookup vs Obj lookup`