Benchmark: var vs let3 - MeasureThat.net

Tests:

var
for(var i = 0; i < 100000; i++){}
var2
for(var i = 0; i < 10; i++){}
let
for(let i = 0; i < 100000; i++){}
let2
for(let i = 0; i < 10; i++){}

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
var
var2
let
let2

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):

LLMs can make mistakes. Check important info.

Let's dive into explaining the provided benchmark.

**What is tested:**

The benchmark measures the performance difference between three different approaches to declaring variables in JavaScript loops:

1. `var`
2. `let` with block scope (as used in `for...of` loops)
3. `let` with function scope (as used in traditional `for` loops)

**Options compared:**

There are two main options being compared:

* `var`: Declares a variable that has function scope, which means it is only accessible within the enclosing function or block.
* `let`: Declares a variable that has block scope, which means it is only accessible within the block where it's declared. In the context of this benchmark, `let` is used in both traditional `for` loops and `for...of` loops.

**Pros and cons:**

1. **var**:
	* Pros:
		+ Lightweight (no syntax overhead)
	* Cons:
		+ Hoisting: Variables declared with `var` can be accessed before they're assigned, which can lead to unexpected behavior.
		+ Variable scope issues (e.g., variables can "leak" into outer scopes).
2. **let** (in traditional `for` loops):
	* Pros:
		+ Block scope ensures variables are only accessible within the block where they're declared.
	* Cons:
		+ Not applicable in this benchmark since we don't have any other `let` variable declarations to compare.
3. **let** (in `for...of` loops):
	* Pros:
		+ Similar benefits as above, with the added benefit of being a more modern and expressive syntax.
	* Cons:
		+ Not a direct comparison since we're only comparing `let` in traditional `for` loops.

**Other considerations:**

The benchmark doesn't account for other factors that might affect performance, such as:

* Function call overhead
* Loop body complexity
* Memory allocation and deallocation

**Library usage:**

There is no library explicitly mentioned in the benchmark definition or test cases. However, it's worth noting that the `for...of` loop syntax uses the Array prototype to iterate over arrays.

**Special JS features or syntax:**

None are explicitly used in this benchmark.

**Benchmark preparation code:**

The provided Script Preparation Code and Html Preparation Code fields are empty, which means the benchmark doesn't require any special setup or environment configurations.

**Other alternatives:**

Some possible alternative approaches for comparing variable declarations could include:

* Using `const` instead of `let`
* Comparing different JavaScript engines (e.g., V8, SpiderMonkey)
* Adding more test cases with different loop bodies and complexities
* Including a baseline test case that uses a legacy JavaScript engine or an older version of the language.

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:67.0) Gecko/20100101 Firefox/67.0

Browser/OS: Firefox 67 on Windows

View result in a separate tab

Test name	Executions per second
var	8060.1 Ops/sec
var2	87511296.0 Ops/sec
let	9732.3 Ops/sec
let2	87877384.0 Ops/sec

Related benchmarks:

var vs let3 (version: 0)

Comparing performance of: var vs var2 vs let vs let2

Created: 5 years ago by: Guest

Jump to the latest result

var

var2

let

let2

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):