Benchmark: let var - MeasureThat.net

Script Preparation code:

"use strict";

Tests:

let
let a = 0; for(let i = 0; i< 1000; i++){ let b = i+2; a+=b; }
var
var a = 0; for(var i = 0; i< 1000; i++){ var b = i+2; a+=b; }

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 llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark data and explain what's being tested, compared, and some pros and cons of each approach.

**Benchmark Definition**

The provided JSON defines two benchmark tests: "let var" and "var". The `Name` field is descriptive of the test, while the `Description` provides a brief explanation of the test case. In this case, both tests involve using `let` or `var` to declare variables within loops.

**Script Preparation Code**

The script preparation code `"use strict";` is executed before each benchmark run. This line enables strict mode in JavaScript, which helps catch common coding mistakes and enforces best practices such as variable declaration and scoping rules.

**Html Preparation Code**

There is no HTML preparation code provided for this benchmark test.

**Individual Test Cases**

The individual test cases are:

1. `let a = 0;for(let i = 0; i< 1000; i++){\r\n\tlet b = i+2;\r\n  \ta+=b;\r\n}`
	* This test case uses the `let` keyword to declare variables within an anonymous loop.
2. `var a = 0;for(var i = 0; i< 1000; i++){\r\n\tvar b = i+2;\r\n  \ta+=b;\r\n}`
	* This test case uses the `var` keyword to declare variables within an anonymous loop.

**Pros and Cons of each approach**

1. **let**
	* Pros:
		+ Encloses variables in their own scope, reducing potential variable pollution.
		+ Prevents re-declarations of variables in the same scope.
	* Cons:
		+ May be slower due to additional checks during execution (block scoping vs. function scoping).
2. **var**
	* Pros:
		+ Faster than `let` due to reduced overhead from block scoping.
	* Cons:
		+ Does not enforce variable declarations, making it more prone to variable pollution and re-declarations.

**Library/Function usage**

There are no explicit library or function references in the benchmark code. However, using libraries like jQuery or other external dependencies can introduce additional variables, DOM manipulation, and potential performance overhead that may affect the test results.

**Special JS features/syntax**

The provided benchmark tests do not use any special JavaScript features or syntax, such as:

* Async/await
* Promises
* Closures
* Arrow functions
* Class syntax

These features would likely introduce additional complexity and potential performance impacts on the benchmark results.

**Alternatives**

Some alternative approaches to measuring JavaScript performance include:

1. V8 Benchmark (Node.js-specific)
2. JSC (Webkit-specific)
3. SpiderMonkey Benchmark (Firefox-specific)
4. Chakra Profiler (Internet Explorer-specific)

These benchmarks typically focus on specific aspects of JavaScript execution, such as garbage collection, interpreter optimizations, or specific library functions.

For measuring general-purpose JavaScript performance, tools like:

1. WebAssembly (WASM) benchmarks
2. JavaScript Core Profiler ( Chrome DevTools)
3. V8 Performance Profiler (Node.js)

are often used to analyze and compare the execution efficiency of different JavaScript engines or libraries.

Please note that each benchmark tool has its strengths and weaknesses, and choosing the right one depends on specific use cases, requirements, and performance characteristics of the JavaScript code being tested.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:106.0) Gecko/20100101 Firefox/106.0

Browser/OS: Firefox 106 on Windows

View result in a separate tab

Test name	Executions per second
let	1874753.8 Ops/sec
var	1865563.5 Ops/sec

Related benchmarks:

let var (version: 0)

let var in loops

Comparing performance of: let vs var

Created: 3 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 llama3.2:3b, generated 27 days ago):