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pos vs neg for loops 2
(version: 2)
Comparing performance of:
for + vs for -
Created:
2 years ago
by:
Registered User
Go to the latest result
Tests:
for +
const length = 999; for (var i=1; i<length; i++) { return i % length; };
for -
const length = 999; for (var i = length; i > 1; i--) { return i % length; };
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
for +
for -
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
2 years ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:126.0) Gecko/20100101 Firefox/126.0
Browser/OS:
Firefox 126 on Windows
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<iframe src="https://measurethat.net/Embed?id=524930" width="100%" height="500px"></iframe>
for -
1943.1M/s
for +
1922.8M/s
View exact numbers
Test name
Executions per second
✓
for -
1,943,062,528 Ops/sec
for +
1,922,760,320 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'll break down the explanation into smaller sections to make it easier to understand. **What is being tested?** The provided benchmark tests two different approaches for looping in JavaScript: using `for +` (i.e., initializing the loop variable inside the loop) versus using `for -` (i.e., initializing the loop variable outside the loop). **Options compared** Two options are being compared: 1. **For Loop with Initialization inside the loop (`for +`)**: * This approach is often used when you need to perform some initialization before the loop starts. 2. *For Loop with Initialization outside the loop (`for -`)*: * This approach is more common and often preferred, as it avoids potential issues with variable scope and lifetime. **Pros and Cons of each approach** **For + (Initialization inside the loop)** Pros: * More flexible, as you can initialize variables before the loop starts * Can be useful when working with complex logic or side effects Cons: * May lead to variable hoisting issues, where variables are moved to the top of their scope, potentially causing unexpected behavior * Can be slower due to additional overhead from initialization and potential reassignments of loop variables **For - (Initialization outside the loop)** Pros: * Typically faster, as there is less overhead from initialization and reassignment of loop variables * Avoids variable hoisting issues, making code more predictable and easier to maintain Cons: * Less flexible than `for +`, as you need to initialize variables before the loop starts * May not be suitable for all scenarios where initialization is necessary **Other considerations** * In modern JavaScript engines, optimization techniques like constant folding, dead code elimination, and inlining can reduce performance differences between these approaches. * The choice of approach ultimately depends on your specific use case, personal preference, and the requirements of your project. **Library usage** There are no libraries mentioned in the provided benchmark definition or test cases. However, some JavaScript engines may provide additional features or optimizations that can impact performance, such as Just-In-Time (JIT) compilation or Ahead-Of-Time (AOT) compilation. **Special JS feature or syntax** The benchmark uses a `for` loop with variable declarations (`var i = ...`). This is a basic syntax feature in JavaScript. The use of `%` operator for modulo calculation also relies on the standard arithmetic operators provided by JavaScript. **Alternatives** If you're looking to test other aspects of performance, you can explore benchmarks that: * Compare different data structures (e.g., arrays, objects, or linked lists) * Measure the impact of caching, memoization, or optimization techniques * Test the performance of specific algorithms (e.g., sorting, searching, or graph traversal) * Evaluate the effects of JavaScript engines' optimization strategies Keep in mind that measuring performance often involves creating test cases that simulate real-world scenarios or explore specific microbenchmarks.
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