Benchmark: const vs var vs let

Tests:

const num
const a = 12109203910293019120392342342;
const string
const a = "12109203910293019120392342342";
var num
var a = 12109203910293019120392342342;
var string
var a = "12109203910293019120392342342";
let num
let a = 12109203910293019120392342342;
let string
const a = "12109203910293019120392342342";

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
const num
const string
var num
var string
let num
let string

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Android 12; Mobile; rv:109.0) Gecko/112.0 Firefox/112.0

Browser/OS: Firefox Mobile 112 on Android

View result in a separate tab

Test name	Executions per second
const num	901633664.0 Ops/sec
const string	902093056.0 Ops/sec
var num	901326144.0 Ops/sec
var string	931544832.0 Ops/sec
let num	890501376.0 Ops/sec
let string	914580160.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll provide an explanation of the benchmark, its options, and other considerations.

**Benchmark Definition:**

The benchmark is defined by a JSON object with four properties:

* `Name`: The name of the benchmark, which is "const vs var vs let".
* `Description`: An empty string indicating that no description is provided for this benchmark.
* `Script Preparation Code` and `Html Preparation Code`: Both are empty strings, suggesting that no specific setup or initialization code is required before running the benchmark.

The purpose of this benchmark is to compare the performance of three JavaScript variable declarations: `const`, `var`, and `let`. This is a fundamental aspect of JavaScript programming, as it affects how variables are scoped, reassigned, and garbage collected.

**Options Compared:**

The benchmark compares the performance of these three variable declarations under different scenarios:

* `const` (constant): Variables declared with `const` cannot be reassigned.
* `var` (variable): Variables declared with `var` can be reassigned.
* `let` (let): Variables declared with `let` are block-scoped, meaning they have their own scope and can be reassigned within that block.

**Pros and Cons:**

Here's a brief summary of the pros and cons of each variable declaration:

* `const`:
	+ Pros:
		- Ensures that variables are not accidentally reassigned.
		- Can improve performance by reducing unnecessary reassignments.
	+ Cons:
		- Prevents reassignment, which may limit flexibility in certain scenarios.
		- May lead to increased memory usage due to the immutability guarantee.
* `var`:
	+ Pros:
		- Allows for flexible assignment and scope control.
		- Can be used in situations where `const` is not suitable.
	+ Cons:
		- May lead to unexpected behavior due to variable hoisting.
		- Can result in performance issues if reassignments are frequent.
* `let`:
	+ Pros:
		- Offers block-scoping, which improves code readability and maintainability.
		- Allows for flexible assignment within specific blocks.
	+ Cons:
		- May lead to slower execution due to the additional scoping mechanism.

**Special JS Features:**

None are explicitly mentioned in the provided benchmark definition or test cases. However, it's worth noting that modern JavaScript versions (ECMAScript 2015 and later) support additional features like `const` functions, which provide a way to declare constants using function syntax.

**Library Usage:**

There is no library usage explicitly mentioned in the benchmark definition or test cases.

**Other Alternatives:**

If you're interested in exploring alternative JavaScript variable declarations or performance optimization techniques, here are some options:

* **ES6 modules**: Use `import` and `export` statements to declare variables and import functions.
* **Arrow functions**: Use arrow functions (`() => { }`) for concise and expressive function declarations.
* **Generator expressions**: Use generator expressions (`({ yield })`) to create iterators and improve code readability.
* **Performance optimization techniques**: Experiment with different optimization strategies, such as minification, compression, or caching, using tools like UglifyJS, Terser, or Rollup.

Keep in mind that the choice of variable declaration or performance optimization technique depends on your specific use case, project requirements, and personal preference.

Related benchmarks:

const vs var vs let (version: 0)

Comparing performance of: const num vs const string vs var num vs var string vs let num vs let string

Created: 4 years ago by: Guest

Jump to the latest result

const num

const string

var num

var string

let num

let string

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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