Benchmark: map vs object - key access

Script Preparation code:

var items = Array.from(Array(1000), (_, x) => ({
    key: x,
    value: x * 10
}));

var objContainer = {};
var mapContainer = new Map();

for (let i = 100; i >= 0; i--) {
    const index = Math.floor(Math.random() * 1000);
    const item = items[index];
    objContainer[item.key] = item;
    mapContainer.set(item.key, item)
}

Tests:

Object access
items.forEach(item => objContainer[item.value])
Map get
items.forEach(item => mapContainer.get(item.value))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object access
Map get

Fastest: N/A

Slowest: N/A

Latest run results:

No previous 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'll break down the provided benchmark and explain what's being tested, compared, and analyzed.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark test case on MeasureThat.net. The benchmark compares the performance of accessing objects using an array (`items`) versus a Map (`mapContainer`). Both arrays are populated with 1000 items each, where each item has a unique key-value pair.

**Script Preparation Code**

The script preparation code defines two containers: `objContainer` (an object) and `mapContainer` (a Map). It then populates these containers by iterating over an array of 1000 random indices. For each index, it creates an item with a unique key-value pair and assigns it to either the object or the map.

**Benchmark Definitions**

There are two individual test cases:

1. **Object Access**: The benchmark definition is `items.forEach(item => objContainer[item.value])`. This code iterates over the array of items and uses each item's value as a key to access its corresponding value in the `objContainer` object.
2. **Map Get**: The benchmark definition is `items.forEach(item => mapContainer.get(item.value))`. This code also iterates over the array of items, but uses the Map's `get()` method to retrieve the value associated with each item's key.

**Comparison**

The test compares the performance of accessing objects using both methods:

* **Object Access**: Using an object (`objContainer`) as a container.
* **Map Get**: Using a Map (`mapContainer`) as a container.

**Pros and Cons**

* **Object Access**:
	+ Pros: Simple, widely supported by most browsers. Objects are often used for caching or storing small amounts of data.
	+ Cons: May have slower performance due to the need to iterate over the array and access each value's corresponding key in the object.
* **Map Get**:
	+ Pros: Generally faster than object access, especially when dealing with large datasets. Maps provide a more efficient way to store and retrieve data using keys.
	+ Cons: Not all browsers support Maps as containers (some older versions of Internet Explorer).

**Library and Purpose**

The `Array.from()` method is used to create an array from an iterable source (in this case, another array). The purpose of this method is to provide a more modern and efficient way to create arrays.

**Special JS Feature or Syntax**

There are no special JavaScript features or syntaxes mentioned in the benchmark definition. However, it's worth noting that the use of `let` and `const` keywords for variable declarations is a newer feature (ES6+).

**Alternatives**

Other alternatives for accessing data include:

* Using an array index directly (`items[index]`)
* Using a `for...in` loop to iterate over the object keys
* Using a library like Lodash or Underscore.js, which provide utility functions for working with arrays and objects.

Keep in mind that the choice of access method depends on the specific use case, performance requirements, and browser support.

Related benchmarks:

map vs object - key access (version: 0)

Comparing performance of: Object access vs Map get

Created: 4 years ago by: Guest

Jump to the latest result

Object access

Map get

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):