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let vs array 2
(version: 0)
is let busted?
Comparing performance of:
arr vs let
Created:
2 years ago
by:
Guest
Go to the latest result
Tests:
arr
let b = []; function a(){ for(let i = 0; i < 10000; i++){ b = [i]; } }
let
function a(){ for(let i = 0; i < 10000; i++){ let c = i; } }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
arr
let
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
2 years ago
)
User agent:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36
Browser/OS:
Chrome 126 on Mac OS X 10.15.7
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<iframe src="https://measurethat.net/Embed?id=530550" width="100%" height="500px"></iframe>
arr
80.4M/s
let
79.9M/s
View exact numbers
Test name
Executions per second
✓
arr
80,377,056 Ops/sec
let
79,942,128 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net. **Benchmark Overview** The benchmark you provided measures the performance difference between using `let` and an array (`[]`) to create local variables in a JavaScript function. The test case consists of two individual tests: "arr" (using an array) and "let" (using the `let` keyword). **Options Compared** In this benchmark, two options are compared: 1. **Using an Array**: In the "arr" test case, an empty array (`[]`) is used to create a local variable `b`. The array is reassigned on each iteration of the loop. 2. **Using the `let` Keyword**: In the "let" test case, the `let` keyword is used to declare a local variable `c`. **Pros and Cons** 1. **Using an Array**: * Pros: Arrays can be reused in various ways within the scope of the function, making them more flexible. * Cons: Reassigning an array on each iteration can lead to performance overhead due to the need for garbage collection. 2. **Using the `let` Keyword**: * Pros: `let` is a block-scoped variable declaration, which means it's redeclared on each execution of the function, making it more suitable for loops where the variable needs to be recreated on each iteration. * Cons: Redeclaring a variable can lead to slower performance due to the overhead of variable creation and garbage collection. **Library and Special JavaScript Features** Neither of these test cases uses any external libraries or special JavaScript features. The code is straightforward and focuses solely on comparing the two variables declaration options. **Other Considerations** When benchmarking JavaScript performance, it's essential to consider factors such as: * Scope: How do different scoping rules (e.g., block scope vs. function scope) affect variable declarations? * Reassignment: How does reassigning a variable (either an array or a `let` variable) impact performance? * Garbage Collection: How do garbage collection cycles impact performance in loops where variables are reassigned? **Alternatives** If you're interested in exploring similar benchmarks, MeasureThat.net offers many other tests and comparisons. Some examples include: * Testing the performance of different variable declaration options (e.g., `const`, `var`, etc.) * Comparing the performance of different data structures (e.g., arrays, objects, sets) * Benchmarking the performance of different JavaScript engines or versions Keep in mind that benchmarking is a complex topic, and results may vary depending on the specific use case and environment.
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