Benchmark: Array vs Object vs Map vs WeakMap access3

Script Preparation code:

var key = {}

var map = new Map();

map.set(key, Math.random())
for (let i = 0; i < 10000; i++) {
  map.set({}, Math.random())
}

var weakMap = new WeakMap()

const a = []
weakMap.set(key, Math.random())
for (let i = 0; i < 10000; i++) {
  const tkey = {}
  a.push(tkey)
  weakMap.set(tkey, Math.random())
}

Tests:

Map.get
map.get(key);
WeakMap.get
weakMap.get(key)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Map.get
WeakMap.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.

Let's break down the provided benchmark definition and test cases.

**Benchmark Definition JSON**

The benchmark definition represents a JavaScript microbenchmarking scenario. It includes:

1. **Script Preparation Code**: This code sets up the environment for the benchmark by creating an object (`key`), a Map instance (`map`), a WeakMap instance (`weakMap`), and an array (`a`). The map and weak map are populated with random values using the `Math.random()` function.
2. **Html Preparation Code**: This field is empty, indicating that no HTML-specific code is required for this benchmark.
3. **Description**: The description of the benchmark is null, suggesting that a detailed explanation or context is not necessary.

**Individual Test Cases**

The test cases measure the performance of two operations:

1. **Map.get(key)**: This operation retrieves a value from a Map instance using the `key` object as the key.
2. **WeakMap.get(key)**: This operation retrieves a value from a WeakMap instance using the `key` object as the key.

**Options Compared**

The benchmark compares the performance of these two operations, which are typically executed in different ways:

* `map.get(key)` uses direct access to retrieve the value associated with the given key. In JavaScript, Map instances maintain an internal hash table that allows for fast lookups.
* `weakMap.get(key)` uses a weak reference to store the key-value pairs. When the key object is garbage collected, the WeakMap instance will automatically remove the corresponding entry from its internal set.

**Pros and Cons of Each Approach**

1. **Direct Access (Map.get)**:
	* Pros: Fast lookups due to the use of an internal hash table.
	* Cons: The Map instance must be explicitly updated when values change, which can add overhead for certain operations.
2. **Weak Reference (WeakMap.get)**:
	* Pros: Allows for automatic removal of entries when keys are garbage collected, reducing memory usage.
	* Cons: Weak references require additional checks to ensure the key still exists in the WeakMap instance.

**Library and Purpose**

In this benchmark, no specific libraries are used. However, the Map and WeakMap instances rely on JavaScript's built-in object implementations.

**Special JS Feature or Syntax**

No special JavaScript features or syntax are used in these test cases.

**Other Considerations**

When choosing between `map.get(key)` and `weakMap.get(key)`, consider the following:

* If you need to frequently update values associated with a key, direct access might be more suitable.
* If memory usage is critical, using a WeakMap instance can help reduce unnecessary entries.
* If you're working in a browser environment, note that some security features may restrict or block WeakMap instances due to concerns about potential security vulnerabilities.

**Alternatives**

If you want to explore alternative approaches for measuring access performance, consider the following:

1. **Array lookups**: Measure the performance of array indices (e.g., `arr[key]`) instead of Map or WeakMap operations.
2. **Hash table implementations**: Compare the performance of different hash table implementations, such as `Object.prototype.hasOwnProperty.call()` versus custom implementations like `fast-forge`.
3. **Other data structures**: Experiment with other data structures, like Sets or Trees, to evaluate their performance characteristics.

These alternatives can provide valuable insights into access patterns and optimization strategies for your specific use case.

Related benchmarks:

Array vs Object vs Map vs WeakMap access3 (version: 0)

Comparing performance of: Map.get vs WeakMap.get

Created: 4 years ago by: Guest

Jump to the latest result

Map.get

WeakMap.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):