Benchmark: var-let-const3 - MeasureThat.net

Tests:

const
const g = { e: [] } g.o = function(x) { g.e.push(...[1,2,3]) } g.o() return g;
let
let g = { e: [] } g.o = function(x) { g.e.push(...[1,2,3]) } g.o() return g;
var
var g = { e: [] } g.o = function(x) { g.e.push(...[1,2,3]) } g.o() return g;

Historical Performance Data aggregated from 6 community runs

Desktop Results:

Other 6 runs

const

47.4M/s

var

20.7M/s

let

20.3M/s

Fastest: const (2.3x faster)

View exact numbers

✓ const: 47,378,768 ops/sec
• var: 20,731,316 ops/sec
• let: 20,346,784 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
const
let
var

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36 OPR/113.0.0.0

Browser/OS: Opera 113 on Windows

View result in a separate tab

const

79.3M/s

var

21.2M/s

let

20.2M/s

View exact numbers

Test name	Executions per second
✓ const	79,321,864 Ops/sec
var	21,198,694 Ops/sec
let	20,197,994 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to help explain the provided benchmark.

**What is being tested?**

The provided benchmark tests three different variable declarations in JavaScript: `const`, `let`, and `var`. Each test case uses a similar script that pushes an array of numbers onto a property of an object, and then returns the resulting object.

**Options compared**

The options being compared are:

1. **`const`**: A constant variable declaration, which means the value cannot be changed after it's declared.
2. **`let`**: A let variable declaration, which allows the value to be changed after it's declared.
3. **`var`**: A traditional variable declaration, which was used before `let` and `const`.

**Pros and Cons of each approach**

* **`const`**:
	+ Pros: Memory efficiency (since the value cannot be changed), predictable behavior.
	+ Cons: Values cannot be reassigned, which might limit flexibility in some cases.
* **`let`**:
	+ Pros: Allows reassignment, which is often necessary in dynamic programming scenarios. Predictable behavior is still maintained since values are only reassigned through `let`.
	+ Cons: Memory usage can increase if values need to be reassigned multiple times.
* **`var`**:
	+ Pros: Legacy compatibility (used before `let` and `const`) and simpler syntax.
	+ Cons: Memory efficiency is lower, since values can be reassigned after initialization.

**Libraries used**

None are mentioned in the provided benchmark definition or test cases. However, it's worth noting that some libraries might use different variable declarations or optimization techniques that could affect benchmark results.

**Special JS features or syntax**

There doesn't appear to be any special JavaScript features or syntax being tested in this benchmark. The focus is on the basic differences between `const`, `let`, and `var`.

**Other alternatives**

If you're interested in exploring other options, consider:

* **Temporal Dead Zone (TDZ)**: A concept introduced in ECMAScript 2020 that can help optimize variable declarations.
* **Arrow functions**: An alternative way to define small functions, which might affect performance or optimization strategies.
* **Block scope** and **let & const hoisting**: Understanding how variables are scoped and hoisted in different contexts can be useful for optimizing JavaScript code.

Keep in mind that these alternatives might not directly relate to the specific benchmark being discussed.

var-let-const3 (version: 0)

Comparing performance of: `const vs let vs var`

Created: one year ago by: Guest

Go to the latest result

const

let

var

Historical Performance Data aggregated from 6 community runs

Desktop Results:

Other 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

var-let-const3 (version: 0)

Comparing performance of: const vs let vs var

Created: one year ago by: Guest

Go to the latest result

const

let

var

Historical Performance Data aggregated from 6 community runs

Desktop Results:

Other 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `const vs let vs var`