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var-let-const3
(version: 0)
Comparing performance of:
const vs let vs var
Created:
one year ago
by:
Guest
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Tests:
const
const g = { e: [] } g.o = function(x) { g.e.push(...[1,2,3]) } g.o() return g;
let
let g = { e: [] } g.o = function(x) { g.e.push(...[1,2,3]) } g.o() return g;
var
var g = { e: [] } g.o = function(x) { g.e.push(...[1,2,3]) } g.o() return g;
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
const
let
var
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
one year ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36 OPR/113.0.0.0
Browser/OS:
Opera 113 on Windows
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=540331" width="100%" height="500px"></iframe>
Test name
Executions per second
const
79321864.0 Ops/sec
let
20197994.0 Ops/sec
var
21198694.0 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'd be happy to help explain the provided benchmark. **What is being tested?** The provided benchmark tests three different variable declarations in JavaScript: `const`, `let`, and `var`. Each test case uses a similar script that pushes an array of numbers onto a property of an object, and then returns the resulting object. **Options compared** The options being compared are: 1. **`const`**: A constant variable declaration, which means the value cannot be changed after it's declared. 2. **`let`**: A let variable declaration, which allows the value to be changed after it's declared. 3. **`var`**: A traditional variable declaration, which was used before `let` and `const`. **Pros and Cons of each approach** * **`const`**: + Pros: Memory efficiency (since the value cannot be changed), predictable behavior. + Cons: Values cannot be reassigned, which might limit flexibility in some cases. * **`let`**: + Pros: Allows reassignment, which is often necessary in dynamic programming scenarios. Predictable behavior is still maintained since values are only reassigned through `let`. + Cons: Memory usage can increase if values need to be reassigned multiple times. * **`var`**: + Pros: Legacy compatibility (used before `let` and `const`) and simpler syntax. + Cons: Memory efficiency is lower, since values can be reassigned after initialization. **Libraries used** None are mentioned in the provided benchmark definition or test cases. However, it's worth noting that some libraries might use different variable declarations or optimization techniques that could affect benchmark results. **Special JS features or syntax** There doesn't appear to be any special JavaScript features or syntax being tested in this benchmark. The focus is on the basic differences between `const`, `let`, and `var`. **Other alternatives** If you're interested in exploring other options, consider: * **Temporal Dead Zone (TDZ)**: A concept introduced in ECMAScript 2020 that can help optimize variable declarations. * **Arrow functions**: An alternative way to define small functions, which might affect performance or optimization strategies. * **Block scope** and **let & const hoisting**: Understanding how variables are scoped and hoisted in different contexts can be useful for optimizing JavaScript code. Keep in mind that these alternatives might not directly relate to the specific benchmark being discussed.
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