Benchmark: let vs const vs var 2

Tests:

let
let aaa = [1]; let count= 1; for(let i=1; i<1000; i++){ aaa.push(aaa[i-1]+1); count*=i/2; }
const
const aaa = [1]; let count= 1; for(let i=1; i<1000; i++){ aaa.push(aaa[i-1]+1); count*=i/2; }
var
var aaa = [1]; let count= 1; for(let i=1; i<1000; i++){ aaa.push(aaa[i-1]+1); count*=i/2; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
let
const
var

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:80.0) Gecko/20100101 Firefox/80.0

Browser/OS: Firefox 80 on Mac OS X 10.14

View result in a separate tab

Test name	Executions per second
let	113091.8 Ops/sec
const	113052.6 Ops/sec
var	113691.9 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the benchmark and explain what's being tested, compared, and its pros and cons.

**What is being tested?**

The benchmark compares the performance of three variable declarations in JavaScript: `let`, `const`, and `var`. The test cases are designed to measure how these variables affect the performance of a specific loop that involves array operations and arithmetic calculations.

**Options compared**

* `let` vs. `const`: This comparison tests whether using a `const` declaration instead of a `let` declaration has an impact on performance.
* `let` vs. `var`: This comparison tests whether using a `let` declaration instead of a `var` declaration has an impact on performance.

**Pros and Cons**

* **Let**: In modern JavaScript, `let` is generally considered the best practice for variable declarations because it provides block scope and helps prevent global variable pollution. However, in this benchmark, we're measuring performance differences between `let` and other options, which might not be as significant since both `const` and `var` can lead to issues like "hoisting" (more on that later).
* **Const**: Using a `const` declaration ensures that the variable's value cannot be changed after initialization. This can be beneficial in certain scenarios, but it also means that any assignment operation will throw an error if the variable is not initialized with a value before being used.
* **Var**: The `var` keyword was widely used in older JavaScript versions and can lead to issues like "hoisting" (more on that later). In modern browsers, you should avoid using `var` for new code due to its limitations.

**Hoisting**

One of the key differences between `let`, `const`, and `var` is how they handle variable declarations. `Var` has a concept called "hoisting," which means that even though you declare a variable without initialization, it gets moved to the top of the scope before the actual code execution starts. This can lead to unexpected behavior if you try to access or modify the variable before its declared.

**Library and syntax**

There is no specific library mentioned in the benchmark configuration, but all tests are running within the standard JavaScript engine used by Firefox (version 80).

No special JavaScript features or syntax are being tested in this benchmark. The focus is on comparing the performance of different variable declarations.

**Alternatives**

If you're interested in testing other aspects of JavaScript performance, here are a few alternatives:

* Compare the performance of different data structures (e.g., arrays vs. objects vs. sets).
* Test the impact of different optimization strategies (e.g., lazy loading vs. eager loading).
* Measure the performance differences between using `this` vs. `super` in inheritance.
* Experiment with various browser-specific features, like Web Workers or WebAssembly.

Keep in mind that each benchmark should focus on a specific aspect of JavaScript performance to ensure accurate and meaningful results.

If you want more detailed information about these alternatives, I can provide some examples and explanation.

Related benchmarks:

let vs const vs var 2 (version: 1)

Comparing performance of: let vs const vs var

Created: 4 years ago by: Registered User

Jump to the latest result

let

const

var

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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