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let vs const v2
(version: 0)
Benchmark.js
Comparing performance of:
let vs const
Created:
2 years ago
by:
Guest
Go to the latest result
Tests:
let
let groups = []; groups.push({a: 10, b:20})
const
const groups = []; groups.push({a: 10, b:20})
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
let
const
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
2 years ago
)
User agent:
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36
Browser/OS:
Chrome 118 on Linux
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<iframe src="https://measurethat.net/Embed?id=508111" width="100%" height="500px"></iframe>
const
54.0M/s
let
53.3M/s
View exact numbers
Test name
Executions per second
✓
const
54,016,044 Ops/sec
let
53,277,696 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided JSON data to understand what is being tested and the options compared. **Benchmark Definition** The benchmark definition is a simple JavaScript code snippet that creates an array `groups` using either the `let` or `const` keyword. The purpose of this benchmark is to compare the performance of declaring a variable with these two keywords in JavaScript. **Options Compared** Two options are being compared: 1. **Let**: Declaring a variable with the `let` keyword. 2. **Const**: Declaring a variable with the `const` keyword. **Pros and Cons of Each Approach** * **Let**: + Pros: Allows reassignment of the variable, which can be useful in certain situations. + Cons: Can lead to memory leaks if not handled properly, as variables are garbage collected when they go out of scope. * **Const**: + Pros: Ensures that the variable is immutable, making it easier to reason about code and reducing the risk of bugs caused by unintended modifications. + Cons: Does not allow reassignment of the variable, which can limit its usefulness in certain situations. **Library or Syntax Used** None are explicitly mentioned in the provided JSON data. However, it's worth noting that modern JavaScript implementations, including those used by Chrome 118, support the `const` keyword for declaring variables, making it a more modern and idiomatic way to declare variables. **Special JS Feature or Syntax (Not Applicable)** Since neither of the benchmark definitions uses any special JavaScript features or syntax (such as async/await, Promises, or Web Workers), no additional explanation is necessary. **Other Alternatives** If you wanted to compare other options for declaring variables in JavaScript, some alternatives could include: * **Var**: An older keyword that declares a variable without specifying its scope. While not recommended in modern code due to potential issues with scope and hoisting. * **Let/Const with Initializers**: Declaring a variable using the `let` or `const` keyword followed by an initializer, like `let groups = []` or `const groups = () => { ... }`. This can help avoid common pitfalls related to uninitialized variables. In summary, this benchmark compares the performance of declaring variables using the `let` and `const` keywords in JavaScript, with a focus on their impact on performance. The use of `const` is considered more modern and idiomatic, but both options have their trade-offs in terms of functionality and usability.
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