Benchmark: Map vs Object - More items

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;
}

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['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 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	6982.4 Ops/sec
Obj lookup	6982.7 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 benchmark and explain what's being tested.

The benchmark is comparing two data structures: Maps (a JavaScript object that stores key-value pairs) and Objects (a generic JavaScript object). The test aims to measure which one provides faster lookup times for accessing values by their keys.

Here are the options being compared:

1. **Map Lookup**: Using a Map object to store key-value pairs, where the key is `'a' + i` and the value is `i`. This means that each iteration of the loop will try to access the value associated with the key `'a' + i`.
2. **Object Lookup**: Using an Object literal (an object created without the `{}` syntax) to store key-value pairs, where the key is also `'a' + i` and the value is `i`. This means that each iteration of the loop will try to access the property associated with the key `'a' + i`.

**Pros and Cons:**

* **Map Lookup**:
	+ Pros:
		- Maps are optimized for fast lookups, as they use a hash table data structure under the hood.
		- This approach can be faster when dealing with large datasets.
	+ Cons:
		- In older JavaScript engines, Map lookups might not work as efficiently due to the overhead of creating and maintaining the hash table.
* **Object Lookup**:
	+ Pros:
		- Objects are generally more familiar to developers, making them easier to work with in many cases.
		- Object property access is often more intuitive than Map key lookup.
	+ Cons:
		- Object lookups can be slower compared to Maps due to the need to traverse the object's prototype chain and then check if the property exists.

**Library Usage:**
There are no external libraries used in this benchmark. However, it's worth noting that some modern JavaScript engines, like V8 (used by Google Chrome), have optimized their Map implementation for performance.

**Special JS Features/Syntax:**
There are a few features used in this benchmark:

* **Template Literals**: The `a` variable is initialized using template literals (`var i = 0, count = 1000, a;`).
* **For Loops with Initialization**: The loops use the `for...of` loop syntax (not explicitly mentioned) for iterating over the range of numbers.

**Alternative Approaches:**
Other ways to compare these two data structures could include:

1. **Arrays vs Maps**: Instead of comparing objects and maps, you could test the performance of accessing values by their indices using arrays versus Maps.
2. **Objects with Properties vs Maps**: You could also compare the performance of accessing properties on an object literal versus a Map.

Keep in mind that the choice of data structure and access method depends on the specific use case and requirements of your application.

Related benchmarks:

Map vs Object - More items (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):