Benchmark: WeakMap vs property access vs array[0] vs symbol access

Script Preparation code:

var weakMap = new WeakMap()
var symbol = Symbol('next');
var object = { a: 1, [symbol]: 1 };
weakMap.set(object, 1);
var array = [1];

Tests:

WeakMap.get
weakMap.get(weakMap)
object.a
object.a
object[symbol]
object[symbol]
array[0]
array[0]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
WeakMap.get
object.a
object[symbol]
array[0]

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36

Browser/OS: Chrome 129 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
WeakMap.get	13467038.0 Ops/sec
object.a	26110638.0 Ops/sec
object[symbol]	14211926.0 Ops/sec
array[0]	25965880.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):

LLMs can make mistakes. Check important info.

This benchmark compares four different approaches to accessing data in JavaScript, specifically focusing on:

1. Using a **WeakMap**.
2. Accessing a property directly from an object.
3. Accessing a property using a **Symbol** as a key.
4. Accessing an element from an array by index.

### Overview of Each Approach

1. **WeakMap.get(weakMap)**:
   - **Explanation**: A `WeakMap` is a collection of key-value pairs where keys are objects and values can be any value. The keys are held weakly, meaning they do not prevent garbage collection if there are no other references to the key object.
   - **Use Case**: WeakMaps are useful for association between objects without creating a strong reference, helping in scenarios like keeping metadata for DOM elements without hindering garbage collection.
   - **Pros**: 
     - Does not prevent garbage collection of keys.
     - Allows for the storage of data that is associated with objects.
   - **Cons**: 
     - It cannot be iterated over and has no keys or size property, which can be limiting.
     - Requires more overhead than direct property access.

2. **object.a**:
   - **Explanation**: This is a direct property access method on a JavaScript object.
   - **Use Case**: Accessing properties is a fundamental operation in JavaScript and is used across various scenarios.
   - **Pros**: 
     - Fast and efficient.
     - Simple syntax and highly readable.
   - **Cons**: 
     - Property keys must be known statically; dynamic access requires different syntax.

3. **object[symbol]**:
   - **Explanation**: This accesses a property of an object using a `Symbol`, which is a unique and immutable identifier.
   - **Use Case**: Symbols create unique keys that avoid name clashes, making them useful in object-oriented programming to define unique properties.
   - **Pros**: 
     - Prevents property name collisions.
     - Allows for properties that are not easily accessible through regular object access.
   - **Cons**: 
     - More complex and less intuitive than standard property access.
     - Symbols cannot be easily serialized or identified without additional handling.

4. **array[0]**:
   - **Explanation**: This accesses the first element of an array using its numeric index.
   - **Use Case**: Arrays are a fundamental data structure in JavaScript, and accessing their elements via indices is a common operation.
   - **Pros**: 
     - Extremely fast and efficient as it directly accesses memory.
     - Simple syntax and common convention in programming.
   - **Cons**: 
     - Less descriptive; context might be lost when only using numbers for access.

### Benchmark Results

From the benchmark results, we observe the following executions per second for each access method:

- `object.a`: 26,110,638.0 executions/second (Fastest)
- `array[0]`: 25,965,880.0 executions/second (Second Fastest)
- `object[symbol]`: 14,211,926.0 executions/second
- `WeakMap.get`: 13,467,038.0 executions/second (Slowest)

### Considerations

- **Performance**: Direct property access (`object.a`) is the fastest, followed closely by array index access (`array[0]`). These traditional object and array accesses are optimal in terms of speed.
- **Use Case Suitability**: While performance is critical, the choice of which method to use should also depend on the application requirements—for example, using a `WeakMap` when associating data with objects where memory management is a concern.
- **Safety and Clarity**: Using symbols enhances property encapsulation, providing safety against naming collisions, albeit at the cost of performance.

### Alternatives

Some alternatives to the approaches tested include:

- **Regular Maps**: Unlike WeakMap, regular Maps also allow key-value pairs but keep strong references to keys, leading to potential memory issues.
- **Prototypes for Inheritance**: By using prototypes, additional properties and methods can be added, offering a different way to manage property access and encapsulation.
- **ES6 Classes**: To provide structured and clearer object-oriented patterns, leveraging classes can encapsulate behavior and properties, improving maintainability in larger codebases.

Overall, the benchmark serves as a vital insight into how different data access methods perform in JavaScript, assisting software engineers in making informed decisions based on both performance and design dilemmas.

Related benchmarks:

WeakMap vs property access vs array[0] vs symbol access (version: 2)

Comparing performance of: WeakMap.get vs object.a vs object[symbol] vs array[0]

Created: 2 months ago by: Registered User

Jump to the latest result

WeakMap.get

object.a

object[symbol]

array[0]

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):