const limit = 10000;const A = function (result){ const a = result + 1; if (a < limit){ return A(a); }}A(0)var limit = 10000;var A = function (result){ var a = result + 1; if (a < limit){ return A(a); }}A(0)let limit = 10000;let A = function (result){ let a = result + 1; if (a < limit){ return A(a); }}A(0)--enable-precise-memory-info flag.
| Test case name | Result |
|---|---|
| Const | |
| VAR | |
| LET |
| Test name | Executions per second |
|---|---|
| Const | 15812.0 Ops/sec |
| VAR | 16787.1 Ops/sec |
| LET | 15709.2 Ops/sec |
Let's break down the provided benchmark and explain what's being tested, compared, and their pros/cons.
What is being tested?
The test cases are designed to compare the performance of three different variable declarations in JavaScript: const, var, and let. Each test case defines a recursive function A that increments its result until it reaches a predefined limit (limit). The tests measure how many times each function executes per second on different browsers.
Options compared
The main options being compared are:
const: A variable declaration that makes the variable immutable, meaning its value cannot be changed after declaration.var: A variable declaration that is function-scoped and does not declare the variable's scope.let: A variable declaration that is block-scoped, which means it only has access to the code within its surrounding let block.Pros/Cons of each approach
const:const cannot be reassigned, which might limit its use in certain scenarios.var:const due to slower variable evaluation and caching.let:const, but only in situations where block scoping is beneficial.Libraries used
None of the test cases use any external libraries or frameworks that would affect the results.
Special JS feature/syntax
There's no specific JavaScript feature or syntax being tested beyond the variable declarations. However, it's worth noting that this benchmark focuses on the performance differences between const, var, and let due to their scoping behavior.
Other alternatives
If you'd like to explore other variable declaration options in JavaScript, consider:
let const: A shorter syntax for declaring both variables at once (e.g., let x = 0; const y = x * 2;).var with the 'with' statement'**: An older technique that allows you to reuse a variable by creating a new scope using the with` statement. However, this is not recommended due to performance and compatibility issues.Keep in mind that these alternatives are not being tested in this specific benchmark.
