Benchmark: weakmap vs closure vs symbols

Script Preparation code:

function A() {
	var x = 0;
	return {
		incr() { x ++ },
		get() { return x },
	}
}
var closure = A();
closure.incr()

var wm = new WeakMap();
function B() {
	var x = {
		incr() { wm.set(x, (wm.get(x) || 0) + 1) },
		get() { return wm.get(x) },
	}
	return x
}
var weakmap = B();
weakmap.incr()


function C() {
	var me = Symbol('me');
	var x = {
		incr() { x[me]++ },
		get() { return x[me] },
		[me]: 0,
	}
	return x
}
var symbols = C();
symbols.incr()

Tests:

closure get
closure.get()
weakmap get
weakmap.get()
closure incr
closure.incr()
weakmap incr
weakmap.incr()
symbol incr
symbols.incr()
symbol get
symbols.get()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
closure get
weakmap get
closure incr
weakmap incr
symbol incr
symbol get

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark measures the performance of three different approaches for incrementing values: closures, WeakMaps, and symbol-based access. The test cases compare the execution time and speed of each approach across various scenarios.

**Options Compared**

1. **Closures**: A closure is a function that has access to its own scope and can capture variables from that scope, even when the outer function has finished executing. In this benchmark, closures are used as a simple incrementer.
2. **WeakMaps**: WeakMaps are a data structure in JavaScript that stores key-value pairs, but unlike regular Maps, they don't prevent keys from being garbage collected. This makes them useful for caching or storing data that doesn't need to be accessed frequently.
3. **Symbols**: Symbols are a primitive data type in JavaScript that can be used as keys in objects, similar to strings. They offer faster lookups compared to strings.

**Pros and Cons of Each Approach**

1. **Closures**:
	* Pros: Simple to implement, flexible, and easy to understand.
	* Cons: Can lead to memory leaks if not handled properly, as the closure retains a reference to the outer scope's variables.
2. **WeakMaps**:
	* Pros: Efficient for caching or storing data that doesn't need frequent access, as they don't prevent keys from being garbage collected.
	* Cons: May have performance overhead due to the use of additional memory, and can lead to unexpected behavior if not used carefully.
3. **Symbols**:
	* Pros: Fast lookups, compact storage, and easy to understand.
	* Cons: May be less flexible than closures or WeakMaps in certain scenarios.

**Library Usage**

In this benchmark, no specific library is used except for the built-in `Symbol` primitive, which is used to create symbols for fast key access.

**Special JS Feature/ Syntax**

The benchmark uses a few special JavaScript features:

1. **WeakMaps**: As mentioned earlier, WeakMaps are a data structure in JavaScript that stores key-value pairs and allows keys to be garbage collected.
2. **Symbols**: Symbols are a primitive data type in JavaScript used for fast lookups.

These features are not specific to any particular syntax or version of JavaScript but rather part of the language's standard library.

**Alternative Approaches**

Other approaches to incrementing values could include:

1. **Arrays**: Using an array to store incremental values and using indexing to update the value.
2. **Numbers**: Storing incremental values as numbers and using arithmetic operations to update the value.
3. **Objects with numerical keys**: Using objects with numerical keys to store incremental values.

These approaches might not offer the same performance benefits as closures, WeakMaps, or symbols but can still be viable alternatives depending on the specific use case.

I hope this explanation helps software engineers understand the benchmark and its underlying mechanics!

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:82.0) Gecko/20100101 Firefox/82.0

Browser/OS: Firefox 82 on Ubuntu

View result in a separate tab

Test name	Executions per second
closure get	252252336.0 Ops/sec
weakmap get	13046157.0 Ops/sec
closure incr	93231160.0 Ops/sec
weakmap incr	5855515.0 Ops/sec
symbol incr	34732160.0 Ops/sec
symbol get	98159720.0 Ops/sec

Related benchmarks:

weakmap vs closure vs symbols (version: 0)

Comparing performance of: closure get vs weakmap get vs closure incr vs weakmap incr vs symbol incr vs symbol get

Created: 4 years ago by: Registered User

Jump to the latest result

closure get

weakmap get

closure incr

weakmap incr

symbol incr

symbol get

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):