Benchmark: Map vs Symbol Property

Script Preparation code:

var to0 = {};
var to1 = {};
var wm = new Map();
var sy = Symbol();
wm.set(to1, 1);
to1[sy] = 1;

Tests:

WeakMap set
wm.set(to0, 1);
Symbol Property set
to0[sy] = 1;
WeakMap get
let r = wm.get(to1);
Symbol Property get
let r = to1[sy];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
WeakMap set
Symbol Property set
WeakMap get
Symbol Property get

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided JSON data and explain what's being tested, compared, and considered in this JavaScript microbenchmark.

**Benchmark Definition**

The benchmark measures the performance difference between using `Symbol` properties versus regular property names when accessing or setting values on an object. The benchmark uses a WeakMap (`wm`) and a plain object (`to0` and `to1`) to store key-value pairs.

**Script Preparation Code**

The script prepares two objects: `to0` and `to1`, which are assigned to the variables `var to0 = {};` and `var to1 = {};`. Additionally, it creates a WeakMap (`wm`) and a Symbol (`sy`) using `var wm = new Map();` and `var sy = Symbol();;`.

The script then sets a key-value pair on the WeakMap using `wm.set(to1, 1);`, which is equivalent to setting a property on `to0` or `to1` with the symbol as its name.

**Html Preparation Code**

There is no HTML preparation code provided in this benchmark.

**Individual Test Cases**

The benchmark consists of four test cases:

1. **WeakMap set**: The script calls `wm.set(to0, 1);`, which sets a key-value pair on the WeakMap.
2. **Symbol Property set**: The script calls `to0[sy] = 1;`, which sets a property on `to0` with the symbol as its name.
3. **WeakMap get**: The script calls `let r = wm.get(to1);`, which retrieves a value from the WeakMap using its key (`to1`).
4. **Symbol Property get**: The script calls `let r = to1[sy];`, which retrieves a value from an object (`to1`) using its property with the symbol as its name.

**Comparison**

The benchmark compares the performance of accessing or setting values on objects using either regular property names or Symbol properties. The test cases measure the time taken for each operation (set and get).

**Pros and Cons**

Using `Symbol` properties has several advantages:

* **Unique property names**: Symbols are unique and cannot be duplicated, making them suitable for use as property names when you need to ensure uniqueness.
* **Performance benefits**: In some cases, using Symbol properties can lead to better performance since they are not subject to the same naming conventions and lookup rules as regular property names.

However, there are also some potential drawbacks:

* **Limited browser support**: Some older browsers may not support Symbols or may have limited functionality around them.
* **Readability concerns**: Using symbols as property names can make code less readable for developers who are not familiar with the feature.

On the other hand, using regular property names has its own advantages and disadvantages:

* **Readability**: Regular property names are generally easier to read and understand than symbols.
* **Browser support**: Most modern browsers support regular property names, making it a safer choice when working on cross-browser compatible code.

**Libraries Used**

The benchmark uses the `Map` class from JavaScript's built-in object model (`var wm = new Map();`) to create the WeakMap. It does not use any external libraries for this purpose.

**Special JS Feature or Syntax**

The benchmark utilizes the Symbol feature in JavaScript, which is a relatively modern addition to the language (introduced in ECMAScript 2015). Symbols are unique, immutable objects that can be used as property names or values in objects. The benchmark tests the performance of using symbols versus regular property names.

**Alternatives**

If you're looking for alternatives to this benchmark or want to explore other approaches to measuring JavaScript performance, consider the following:

* **Benchmarking libraries**: Libraries like Benchmark.js or Microbenchmark allow you to write more complex benchmarks and run them on multiple browsers.
* **Performance testing frameworks**: Frameworks like Jest or Mocha provide built-in support for running tests and benchmarks in a more structured way.
* **Native browser performance testing tools**: Many modern web browsers have built-in performance testing tools, such as Chrome DevTools' Performance tab.

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36

Browser/OS: Chrome 104 on Windows

View result in a separate tab

Test name	Executions per second
WeakMap set	6627580.0 Ops/sec
Symbol Property set	6686966.5 Ops/sec
WeakMap get	6554743.0 Ops/sec
Symbol Property get	7040482.5 Ops/sec

Related benchmarks:

Map vs Symbol Property (version: 0)

Comparing performance of: WeakMap set vs Symbol Property set vs WeakMap get vs Symbol Property get

Created: 2 years ago by: Guest

Jump to the latest result

WeakMap set

Symbol Property set

WeakMap get

Symbol Property get

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):