Benchmark: Adding fields to functions

Script Preparation code:

function unmangle(s) {
  return s.replace(/\$\d+$/, "").replace("$_", "-");
}

Tests:

fun-assign
var f; var sum = 0; for(var i = 0; i <= 100000; i += 1) { f = function(j) { return j; }; f.name = "fun-name"; sum += f(i); } console.log(unmangle(f.name));
no-assign-named
var f; var sum = 0; for(var i = 0; i <= 100000; i += 1) { f = function fun$_name$2(j) { return j; }; sum += f(i); } console.log(unmangle(f.name));
object-assign
var f; var sum = 0; var o = {}; for(var i = 0; i <= 100000; i += 1) { f = function f(j) { return j; }; o.name = "un$_name$3"; sum += f(i); } console.log(unmangle(f.name + o.name));
define-prop
var f; var sum = 0; for(var i = 0; i <= 100000; i += 1) { f = function(j) { return j; }; Object.defineProperty(f, 'name', {value: 'fun-name'}); sum += f(i); } console.log(f.name);
fun-assign mangled
var f; var sum = 0; for(var i = 0; i <= 100000; i += 1) { f = function(j) { return j; }; f.name = "fun$_name$1"; sum += f(i); } console.log(unmangle(f.name));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
fun-assign
no-assign-named
object-assign
define-prop
fun-assign mangled

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 dive into the explanation.

**Benchmark Purpose:**

The benchmark measures how fast JavaScript functions can be assigned and used in different ways, which is relevant for understanding performance optimization techniques, especially when it comes to code readability, maintainability, and execution speed.

**Options Compared:**

Four options are compared:

1. **Assignment without naming**: `f = function(j) { return j; }`
2. **Assignment with named object**: `var o = {}; f = function f(j) { return j; } o.name = "un$_name$3";`
3. **Property definition using Object.defineProperty**: `Object.defineProperty(f, 'name', {value: 'fun-name'})`
4. **Mangled assignment**: `f = function fun$_name$2(j) { return j; }`

**Pros and Cons of Each Approach:**

1. **Assignment without naming**: This approach is simple and fast but also less readable and maintainable, as the variable name is not defined until after it's used.
	* Pros: Fast execution speed
	* Cons: Less readable, maintainable, and less debuggable
2. **Assignment with named object**: This approach uses a named object to store the function, which makes it more readable and maintainable than the first option but still slower due to the overhead of creating an object.
	* Pros: More readable, maintainable, and easier to debug
	* Cons: Slower execution speed due to object creation
3. **Property definition using Object.defineProperty**: This approach uses a property descriptor to define the function name, which is more efficient than creating a new object or using a named object.
	* Pros: Fast execution speed, still readable and maintainable
	* Cons: Less intuitive for beginners, requires understanding of property descriptors
4. **Mangled assignment**: This approach assigns the function to itself with a mangled name, which can lead to confusion and is generally discouraged in production code.
	* Pros: None notable (it's just a variation of the first option)
	* Cons: Less readable, maintainable, and less debuggable

**Other Considerations:**

When evaluating these options, it's essential to consider the trade-offs between execution speed, readability, maintainability, and ease of debugging.

**Alternative Approaches:**

Additional approaches could be explored, such as:

1. Using a function constructor with an immediate invoked function expression (IIFE): `var f = new Function('j', 'return j;');`
2. Utilizing ES6 features like template literals or the `function` expression's default parameter:
	* `f = (...args) => args[0];`

However, these alternatives might not be directly comparable to the original options in terms of performance and readability.

For those interested in exploring alternative approaches or gaining a deeper understanding of JavaScript performance optimization techniques, I recommend checking out resources like MDN Web Docs, W3Schools, or online forums dedicated to JavaScript development.

Latest run results:

Run details: (Test run date: 7 years ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0

Browser/OS: Firefox 50 on Ubuntu

View result in a separate tab

Test name	Executions per second
fun-assign	9.0 Ops/sec
no-assign-named	173.9 Ops/sec
object-assign	168.7 Ops/sec
define-prop	10.2 Ops/sec
fun-assign mangled	9.2 Ops/sec

Related benchmarks:

Adding fields to functions (version: 0)

Comparing performance of: fun-assign vs no-assign-named vs object-assign vs define-prop vs fun-assign mangled

Created: 7 years ago by: Guest

Jump to the latest result

fun-assign

no-assign-named

object-assign

define-prop

fun-assign mangled

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):