Benchmark: let & var 2 - MeasureThat.net

Tests:

let
let foo = "foo" foo = "bar"
var
let foo = "foo" foo = "bar"

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
let
var

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gemma2:9b, generated 29 days ago):

LLMs can make mistakes. Check important info.

This benchmark on MeasureThat.net compares the performance of using `var` and `let` to declare variables in JavaScript.

**What's being tested:**

Both test cases involve the following code:

```javascript
// var version
var foo = "foo";
foo = "bar";

// let version
let foo = "foo";
foo = "bar";
```

The benchmark measures how many times this simple assignment operation can be completed per second.

**Options compared:**

* **`var`**: The traditional way to declare variables in JavaScript. Variables declared with `var` have function scope, meaning they are accessible anywhere within the same function.
* **`let`**: Introduced in ES6 (ECMAScript 2015), `let` also declares variables but has block scope. This means a variable declared with `let` is only accessible within the block of code where it's defined (e.g., inside an if statement or a loop).

**Pros and Cons:**

* **`var`**: 
    * **Pro**: Familiar to older JavaScript developers.
    * **Con**: Can lead to unexpected behavior due to function scope, making it harder to track variable usage and potential conflicts.
* **`let`**: 
    * **Pro**: Block scoping helps prevent accidental variable reassignments or unintended access, leading to more predictable code.
    * **Con**: Requires understanding of ES6 syntax, which might not be familiar to all developers.

**Other Considerations:**

While this benchmark focuses on raw execution speed, real-world performance can be influenced by factors like:

* **Code Complexity**: The impact of `var` vs. `let` becomes more significant in complex code with nested blocks and multiple variable declarations.
* **Linting and Code Style**: Modern JavaScript projects often enforce the use of `let` for better code readability and maintainability.

**Alternatives:**

The benchmark only considers two options, but other approaches exist:

* **`const`**: Similar to `let`, but used for declaring constants (variables whose value should not be reassigned).

Let me know if you have any more questions!

Latest run results:

Run details: (Test run date: 6 years ago)

User agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0

Browser/OS: Firefox 60 on Windows 7

View result in a separate tab

Test name	Executions per second
let	1078523776.0 Ops/sec
var	1317644672.0 Ops/sec

Related benchmarks:

let & var 2 (version: 0)

Comparing performance of: let vs var

Created: 6 years ago by: Guest

Jump to the latest result

let

var

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gemma2:9b, generated 29 days ago):