Benchmark: function vs class

Script Preparation code:

var arr = [];

Tests:

function declaration
function functionDeclaration(item) { arr.push(item); } for (let i = 1; i < 10000; i++) { functionDeclaration(i); }
function expression
var functionExpression = function(item) { arr.push(item); }; for (let i = 1; i < 10000; i++) { functionExpression(i); }
class
class Test { constructor(item) { this.item = item; } addItem(){ arr.push(this.item) } } for (let i = 1; i < 10000; i++) { new Test(i).addItem(); }

Historical Performance Data aggregated from 12 community runs

Desktop Results:

Firefox 12 runs

function declaration

2K/s

function expression

1K/s

class

136/s

Fastest: function declaration (15.6x faster)

View exact numbers

✓ function declaration: 2,121 ops/sec
• function expression: 1,378 ops/sec
• class: 136 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
function declaration
function expression
class

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:149.0) Gecko/20100101 Firefox/149.0

Browser/OS: Firefox 149 on Windows

View result in a separate tab

function declaration

2K/s

function expression

1K/s

class

166/s

View exact numbers

Test name	Executions per second
✓ function declaration	2,353 Ops/sec
function expression	1,277 Ops/sec
class	166 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 world of JavaScript microbenchmarks!

The provided JSON represents a benchmark test that compares three different approaches to achieve the same goal: pushing items onto an array.

**Approaches being compared:**

1. **Function Declaration**: This approach uses a traditional function declaration (e.g., `function foo(item) { arr.push(item); }`) and calls it repeatedly.
2. **Function Expression**: This approach uses a function expression (e.g., `const bar = function(item) { arr.push(item); };`) and calls it repeatedly.
3. **Class**: This approach uses a class definition (e.g., `class MyClass { constructor(item) { this.item = item; } addItem() { arr.push(this.item); } }`) and creates instances of the class, calling the `addItem()` method.

**Pros and Cons:**

* **Function Declaration**:
	+ Pros: Easy to understand and implement.
	+ Cons: May lead to slower performance due to function lookup overhead.
* **Function Expression**:
	+ Pros: Can be faster than traditional function declarations since it avoids the function lookup step.
	+ Cons: May be less readable or easier to mistake due to its concise syntax.
* **Class**:
	+ Pros: Encapsulates data and behavior, making code more modular and maintainable.
	+ Cons: May incur overhead due to object creation and method invocation.

**Library usage:** None of the approaches explicitly use a library. However, it's worth noting that some browsers (e.g., V8 in Chrome) have optimized implementations for certain JavaScript constructs, like closures or function declarations.

**Special JS feature or syntax:** None mentioned.

Now, let's look at the benchmark results:

The top result shows that **Function Expression** outperforms the other two approaches on this particular test case, with an execution rate of 1876.09 executions per second. The middle result indicates that **Function Declaration** is slightly slower than Function Expression but faster than Class. The bottom result shows that **Class** is the slowest approach in this benchmark.

If you're interested in exploring alternative approaches or optimizing your own JavaScript performance, here are some additional considerations:

* Use a profiler to identify bottlenecks and optimize specific parts of your code.
* Consider using just-in-time (JIT) compilation libraries like V8 or SpiderMonkey to improve performance.
* Take advantage of modern browser features like WebAssembly or Worker threads for concurrent execution.
* Experiment with different language features, such as async/await or generators, which can impact performance.

For a broader perspective on JavaScript benchmarking and optimization, you might want to explore other resources, such as:

* The Mozilla Developer Network (MDN) documentation on performance and optimization.
* WebAssembly benchmarks and tutorials.
* The popular benchmarking framework, Benchmark.js.
* Online communities like Reddit's r/learnjavascript or Stack Overflow's JavaScript tag.

function vs class (version: 0)

Comparing performance of: `function declaration vs function expression vs class`

Created: 5 years ago by: Guest

Go to the latest result

function declaration

function expression

class

Historical Performance Data aggregated from 12 community runs

Desktop Results:

Firefox 12 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

function vs class (version: 0)

Comparing performance of: function declaration vs function expression vs class

Created: 5 years ago by: Guest

Go to the latest result

function declaration

function expression

class

Historical Performance Data aggregated from 12 community runs

Desktop Results:

Firefox 12 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

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Comparing performance of: `function declaration vs function expression vs class`