Benchmark: IIFE vs regular code

Tests:

IIFE
for (let i = 0; i < 100; i++) { const a = (() => 4)(); }
regular code
for (let i = 0; i < 100; i++) { const a = 4; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
IIFE
regular code

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:120.0) Gecko/20100101 Firefox/120.0

Browser/OS: Firefox 120 on Windows

View result in a separate tab

Test name	Executions per second
IIFE	19740382.0 Ops/sec
regular code	12293789.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**Benchmark Definition and Preparation Code**

The benchmark is defined as "IIFE vs regular code", which means it compares the performance of two types of code: Immediately Invoked Function Expressions (IIFEs) and regular code. The preparation code for this benchmark is empty, indicating that no specific setup or initialization is required before running the tests.

**Options Compared**

The options being compared are:

1. IIFE (Immediately Invoked Function Expression)
2. Regular code

These two approaches differ in how they declare and execute functions.

**Pros and Cons of Each Approach**

### IIFE

A traditional IIFE is a function that is immediately executed after it's defined, thanks to the self-invoking syntax `(function() { ... })()` or `var func = (function() { ... }); func();`. This approach provides:

* **Encapsulation**: The function is executed in its own scope, which can help prevent global variable pollution.
* **Closure**: IIFEs can create closures, allowing them to access variables from the surrounding scope.

However, using an IIFE for this benchmark may introduce unnecessary overhead due to:

* **Function creation and lookup**: JavaScript engines need to allocate memory for function objects and look up functions at runtime, which can be slow.
* **Scope resolution**: The engine needs to resolve the scope of the IIFE, which involves checking for nested scopes.

### Regular Code

Regular code simply declares a variable `a` and assigns it the value `4`, without any immediate execution. This approach provides:

* **Simpler syntax**: It's shorter and more concise than an IIFE.
* **Less overhead**: There's no function creation, lookup, or scope resolution overhead.

However, using regular code for this benchmark may lead to:

* **Global variable pollution**: The `a` variable is declared in the global scope, which can pollute the namespace.

**Library Usage**

There is no explicit library usage mentioned in the provided benchmark definition or test cases. However, some JavaScript engines might use internal libraries or utilities to optimize or improve performance.

**Special JS Feature/Syntax**

The benchmark uses a special syntax: `() => 4`. This is an arrow function expression, which was introduced in ECMAScript 2015 (ES6) as part of the syntax for defining small functions. The arrow function has several advantages over traditional functions:

* **Compact syntax**: It's shorter and more concise.
* **Implicit `this`**: The arrow function inherits the `this` value from its surrounding scope.

However, it also introduces some limitations:

* **Limited compatibility**: Arrow functions might not be supported by older JavaScript engines or environments.
* **Different behavior in certain contexts**: Inheritance and object prototype chain handling can differ between traditional functions and arrow functions.

**Other Alternatives**

Alternative approaches to compare performance include:

* Using `Function` constructors instead of IIFEs
* Creating a single function that returns another function (e.g., using the `createFunction` method)
* Comparing different algorithmic implementations for simple arithmetic operations

Keep in mind that these alternatives might introduce additional complexity or overhead, and may not be as straightforward to implement as the original benchmark.

Related benchmarks:

IIFE vs regular code (version: 0)

Check if IIFE have a negative runtime impact or if they are optimized away

Comparing performance of: IIFE vs regular code

Created: 2 years ago by: Guest

Jump to the latest result

IIFE

regular code

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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