Benchmark: Get Size (Map vs Object)

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.size; }
Obj lookup
for (i = 0; i < count; i++) { a = Object.keys(obj).length; }

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:

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

LLMs can make mistakes. Check important info.

I'd be happy to explain the benchmark and its components.

**Benchmark Overview**

The provided benchmark measures the performance difference between using a `Map` data structure versus an object (`Object`) in JavaScript for fast lookups. The test case consists of two iterations:

1. Creating a large map and object, with 1000 entries, and storing integer values.
2. Measuring the time it takes to get the size (number of keys) of both the map and object using a `for` loop.

**Options Compared**

Two options are being compared in this benchmark:

1. **Map**: A built-in JavaScript data structure that stores key-value pairs, allowing for fast lookups using the `size` property.
2. **Object**: A built-in JavaScript data structure that stores key-value pairs, but does not have a built-in method for getting the size of its keys.

**Pros and Cons**

**Map:**

Pros:

* Fast lookups (average time complexity is O(1))
* Efficient use of memory

Cons:

* Requires more code to achieve the same result as an object
* May require additional libraries or features not available in older browsers

**Object:**

Pros:

* Simple to implement and requires less code
* Works on older browsers that don't support `Map`

Cons:

* Slower lookups (average time complexity is O(n))
* May lead to more memory allocation and garbage collection

**Other Considerations**

The benchmark does not consider other factors that might affect performance, such as:

* Data type: Using a large number of entries with different data types may impact performance.
* Browser version and engine: Different browsers have varying levels of optimization for `Map` and object lookups.
* Hardware: The test is run on a desktop device, but benchmarking on mobile devices or other platforms might yield different results.

**Library Used**

None is explicitly mentioned in the provided benchmark definition. However, if a library like Lodash is used to implement the map and object creation, it would be worth noting that some of its functions may introduce additional overhead.

**Special JavaScript Feature or Syntax**

The use of the `var` keyword for variable declarations is an older syntax. In modern JavaScript, `let` and `const` are recommended instead. However, this difference in syntax does not significantly impact performance in this specific benchmark.

Overall, this benchmark provides a simple and concise way to compare the performance of using a `Map` versus an object for fast lookups in JavaScript.

Related benchmarks:

Get Size (Map vs Object) (version: 0)

Lookup of map vs object

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

No previous run results

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