Benchmark: Map vs Object - More items4

Script Preparation code:

var map = new Map();
var obj = {};
for (let i = 0; i < 50; i++) {
  map.set('a' + i, i);
  obj['a' + i] = i;
}
obj = Object.freeze(obj)

var i = 0, count = 1000, a;

Tests:

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

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 year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36

Browser/OS: Chrome 126 on Windows

View result in a separate tab

Test name	Executions per second
Map lookup	5632.7 Ops/sec
Obj lookup	4596.8 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into explaining the provided benchmark.

**Benchmark Definition**

The benchmark measures the performance difference between two data structures: Maps and Objects in JavaScript. Specifically, it tests the lookup performance of these data structures when accessing elements using string keys.

**Options Compared**

Two options are compared:

1. **Map**: A Map is a data structure that stores key-value pairs. It provides fast lookups, insertions, and deletions. In this benchmark, a Map is used to store values with string keys.
2. **Object**: An Object is a data structure that stores key-value pairs, similar to a Map. However, Objects are often used for more complex scenarios, such as inheritance or prototype chains.

**Pros and Cons of Each Approach**

* **Map**:
	+ Pros: Fast lookups (average O(1) time complexity), efficient insertion and deletion.
	+ Cons: May have additional overhead due to the Map's internal implementation, which may not be as optimized for certain use cases.
* **Object**:
	+ Pros: Often easier to work with, especially when using inheritance or prototype chains. Objects can also leverage existing libraries and frameworks that optimize their lookup performance.
	+ Cons: Lookups are generally slower than Maps (average O(1) time complexity), especially when dealing with large numbers of keys.

**Library Used**

Neither the Map nor Object data structure uses a library in this benchmark, as they are built-in JavaScript features. However, if you were to use an external library for your own implementation, some popular options include:

* For Maps: `js- map` or `lodash.map`
* For Objects: No additional library is required, but libraries like `lodash.object` can provide optimized lookup methods.

**Special JS Feature or Syntax**

The benchmark uses a special syntax feature in JavaScript known as **"Template Literals"**, which allows you to embed expressions inside string literals using the `\r\n` escape sequence. This syntax is used in the preparation code snippet: `"var i = 0, count = 1000, a;"`.

**Other Considerations**

When working with large datasets or performance-critical applications, consider factors such as:

* Cache locality: How well do the data structures' internal implementations cache frequently accessed elements?
* Data distribution: How evenly distributed are the keys across the data structure?
* Computational overhead: Are there any additional costs associated with operations like insertion, deletion, or iteration?

**Alternative Benchmarks**

If you're interested in exploring alternative benchmarking scenarios:

* You could test the performance of different caching mechanisms, such as `WeakMap` vs. `Object Cache`.
* Compare the performance of various sorting algorithms, such as QuickSort vs. Merge Sort.
* Benchmark the execution time of different JavaScript engines or interpreters.

Feel free to ask if you have any further questions!

Related benchmarks:

Map vs Object - More items4 (version: 0)

Lookup of map vs object

Comparing performance of: Map lookup vs Obj lookup

Created: one year 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):