Benchmark: Closure vs arrow function

Script Preparation code:

var msg = "test";
var sayClosure = function() {
  var d = msg;
}

this.msg = "test";
var sayArrow = () => {
  var d =  this.msg;
}

Tests:

Closure
sayClosure();
Arrow function
sayArrow();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Closure
Arrow function

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:122.0) Gecko/20100101 Firefox/122.0

Browser/OS: Firefox 122 on Windows

View result in a separate tab

Test name	Executions per second
Closure	627074496.0 Ops/sec
Arrow function	620963712.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided benchmark compares the performance of two JavaScript approaches: closures and arrow functions. A closure is a function that has access to its outer scope's variables, whereas an arrow function does not have this same level of scoping.

**Script Preparation Code Analysis**

The script preparation code defines two functions:

1. `sayClosure`: This function creates a variable `d` within the closure, which captures the value of `msg`. The closure also captures the outer scope's `msg` variable.
2. `sayArrow`: This is an arrow function that attempts to capture the `this` context and the value of `msg`. However, due to the nature of arrow functions, it will not inherit the `msg` property from the outer scope.

**Options Comparison**

The two options being compared are:

1. **Closures**: Closures create a new scope for variables, allowing them to be accessed within the function's execution context. This approach has its pros and cons:
	* Pros: Can capture variables from the surrounding scope, creating a self-contained environment.
	* Cons: May lead to memory leaks if not properly cleaned up, as variables are retained across function calls.
2. **Arrow Functions**: Arrow functions do not create a new scope for variables; instead, they inherit the `this` context and variable values from the surrounding scope. This approach has its pros and cons:
	* Pros: Simplifies code by avoiding unnecessary scoping mechanisms, reducing memory usage.
	* Cons: Does not allow capturing of outer scope variables in the same way as closures.

**Library Analysis**

There is no explicit library mentioned in the benchmark setup or test cases. However, it's worth noting that JavaScript engines like Firefox may use internal libraries and optimizations to execute these functions.

**Special JS Features/Syntax**

The benchmark does not utilize any special JavaScript features or syntax beyond what is standard for the language. This makes it a great example for demonstrating basic scoping concepts in JavaScript.

**Other Considerations**

When evaluating performance differences between closures and arrow functions, consider the following factors:

* **Code size and complexity**: Closures can create additional scope overhead, potentially affecting execution time.
* **Memory management**: Closures may require more memory due to retained variables, whereas arrow functions do not capture outer scope variables.
* **Scoping**: Understand how each approach handles variable scoping and its implications on code behavior.

**Alternative Approaches**

If you need to benchmark other JavaScript approaches or features, consider the following alternatives:

1. **Template literals vs string concatenation**: Compare the performance of template literals versus string concatenation for building strings.
2. **For loops vs array methods**: Benchmark the execution speed of traditional `for` loops against array methods like `forEach()` or `map()`.
3. **Object property access vs array indexing**: Compare the performance of accessing object properties versus array indices.

These alternatives can help you explore specific aspects of JavaScript performance and optimization.

Related benchmarks:

Closure vs arrow function (version: 0)

Comparing performance of: Closure vs Arrow function

Created: 9 years ago by: Guest

Jump to the latest result

Closure

Arrow function

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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