Benchmark: __proto__ vs assign field

Script Preparation code:

var proto = {
	fn() {},
  	fn2() {},
  	fn3() {},
  	afn: () => {},
    afn2: () => {},
    afn3: () => {}
}

var fn = function () {}
var fn2 = function () {}
var fn3 = function () {}
var afn = () => {}
var afn2 = () => {}
var afn3 = () => {}

Tests:

fn set proto
var myfn = () => {} myfn.__proto__ = proto
assign field
var myfn2 = () => {} myfn2.fn = fn myfn2.fn2 = fn2 myfn2.fn3 = fn3 myfn2.afn = afn myfn2.afn2 = afn2 myfn2.afn3 = afn3

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
fn set proto
assign field

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
fn set proto	15971248.0 Ops/sec
assign field	5498877.5 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmarking test cases.

**What is being tested?**

The two test cases compare the performance of setting the prototype chain (`__proto__`) versus assigning fields to an object using dot notation or bracket notation (`fn = function () {}`, `myfn.__proto__ = proto`). The focus is on the overhead introduced by these different approaches when accessing and modifying properties.

**Options compared:**

1. **Setting the prototype chain (`__proto__`)**:
	* Pros:
		+ Can be a more concise way to set multiple properties at once.
		+ May be optimized by some JavaScript engines, as it can utilize built-in optimization paths for prototype chains.
	* Cons:
		+ Can lead to slower performance due to the overhead of setting the prototype chain, especially if the object has many properties.
		+ May not work correctly in all scenarios, such as when using Object.create() or other techniques that modify the prototype chain dynamically.
2. **Assigning fields using dot notation (`fn = function () {}`)**:
	* Pros:
		+ Typically faster than setting the prototype chain, as it avoids the overhead of modifying the prototype chain.
		+ Often used in modern JavaScript codebases, so engines may have optimized for this approach.
	* Cons:
		+ Requires more lines of code to set multiple properties, which can lead to slower performance if many properties need to be set.

**Other considerations:**

* The use of `Object.create()` or other methods that modify the prototype chain dynamically may affect the results. Setting the prototype chain using `__proto__` might not work correctly in these cases.
* Some JavaScript engines, like SpiderMonkey (used by Firefox), have optimized for dot notation assignments, which could impact performance.

**Library and syntax:**

There are no libraries mentioned in this benchmarking test case. However, some engines might use internal optimization techniques that rely on the specific syntax used.

**Special JS feature or syntax:**

The `__proto__` syntax is a built-in JavaScript feature for setting the prototype chain of an object. It's not a special feature per se, but it does demonstrate how to set multiple properties at once and how some engines might optimize this approach.

**Alternatives:**

If you're interested in exploring alternative approaches, consider these:

* Using `Object.assign()` or similar methods that create new objects with specific properties.
* Utilizing modern JavaScript features like object literals (`{ prop1: value1, prop2: value2 }`) to set multiple properties at once.

Keep in mind that the best approach will depend on the specific use case and requirements. These benchmarks can help you compare performance under different scenarios, but it's essential to consider other factors when writing production code.

Related benchmarks:

proto vs assign field (version: 0)

Comparing performance of: fn set proto vs assign field

Created: 2 years ago by: Registered User

Jump to the latest result

fn set proto

assign field

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

__proto__ vs assign field (version: 0)

Comparing performance of: fn set proto vs assign field

Created: 2 years ago by: Registered User

Jump to the latest result

fn set proto

assign field

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

proto vs assign field (version: 0)