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const vs var vs let fork
(version: 0)
Comparing performance of:
const num vs const string vs var num vs var string vs let num vs let string
Created:
5 years ago
by:
Guest
Jump to the latest result
Tests:
const num
const a = 12109203910293019120392342342; const b = 12109203910293019120392342342; const c = 12109203910293019120392342342; const d = 12109203910293019120392342342;
const string
const a = "12109203910293019120392342342";
var num
var a = 12109203910293019120392342342; var b = 12109203910293019120392342342; var c = 12109203910293019120392342342; var d = 12109203910293019120392342342;
var string
var a = "12109203910293019120392342342";
let num
let a = 12109203910293019120392342342; let b = 12109203910293019120392342342; let c = 12109203910293019120392342342; let d = 12109203910293019120392342342;
let string
const a = "12109203910293019120392342342";
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (6)
Previous results
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Test case name
Result
const num
const string
var num
var string
let num
let string
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of JavaScript microbenchmarks! **Overview** MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The provided JSON data represents a benchmark with six test cases, each testing different approaches for variable declarations (const, var, and let). **Variable Declaration Approaches** The benchmark tests four variable declaration approaches: 1. **const**: A constant value is assigned to multiple variables. 2. **var**: A variable is declared using the traditional `var` keyword, with multiple assignments. 3. **let**: A variable is declared using the `let` keyword, with multiple assignments. 4. **const fork** (not explicitly tested): This approach is not shown in the provided data, but it's worth mentioning that some browsers might optimize const variables by reusing the same storage location for all assigned values. **Options Compared** The benchmark compares the performance of each variable declaration approach: * **const**: A constant value is assigned to multiple variables. + Pros: Can provide better memory management and less garbage collection overhead. + Cons: Variables declared with `const` cannot be reassigned. * **var**: A variable is declared using the traditional `var` keyword, with multiple assignments. + Pros: None notable. + Cons: Can lead to performance issues due to scope resolution and reassignment overhead. * **let**: A variable is declared using the `let` keyword, with multiple assignments. + Pros: More memory efficient than `var`, but slower than `const`. + Cons: Variables declared with `let` are not hoisted like variables in `var`. **Library and Special Features** None of the test cases use any external libraries or special JavaScript features. The benchmark focuses solely on testing the performance difference between different variable declaration approaches. **Other Considerations** * **Hoisting**: In modern browsers, some variables declared with `const` or `let` are hoisted to the top of their scope, while variables in `var` are not hoisted. * **Scope Resolution**: The `var` keyword can lead to slower performance due to scope resolution, as the browser needs to resolve the scope of each variable assignment. **Alternatives** If you're interested in creating your own JavaScript microbenchmarks or want to explore other approaches, consider using tools like: * jsperf (now deprecated) * Benchmark.js * js-benchmark These tools provide more advanced features and options for testing different aspects of JavaScript performance.
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