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for-test
(version: 0)
Comparing performance of:
no cache length vs with cache length
Created:
7 years ago
by:
Guest
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Tests:
no cache length
const arr = new Array(10000) for (let i = 0; arr.length < 1000; i++){ console.log(i); }
with cache length
const arr = new Array(10000) for (let i = 0, l = arr.length; i < l; i++){ console.log(i); }
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Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
no cache length
with cache length
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'll break down what's being tested in the provided benchmark. **Benchmark Overview** The benchmark measures the execution time of two identical JavaScript loops that iterate over an array. The difference lies in how the array length is accessed: 1. **No cache**: `arr.length < 1000` (line 4) 2. **With cache**: `l = arr.length` (line 5) **Comparison Options** The benchmark compares the performance of these two approaches, which involves a simple but common optimization technique in JavaScript. Pros and Cons: * **No Cache Length**: + Pros: None obvious. + Cons: This approach can be slower due to the overhead of the `length` property being accessed multiple times. In older JavaScript engines, accessing `arr.length` might trigger a reevaluation of the array's length, leading to unnecessary work. * **With Cache Length**: + Pros: By caching the result of `arr.length`, this approach avoids the repeated access and potential overhead associated with it. This optimization is particularly effective in modern JavaScript engines that have optimized the `length` property's behavior. + Cons: This approach requires a single cache operation, which might add to the overall benchmark time if executed frequently. **Library and Syntax Considerations** There are no notable libraries or special JavaScript features used in this benchmark. The focus is solely on comparing the two loop approaches. **Alternative Approaches** Other optimizations that could be considered in similar benchmarks include: * Using `let` instead of `var` for loop variables, as it avoids global variable creation and reassignment. * Using `for...of` loops instead of traditional `for` loops, which can be more efficient for certain use cases. * Optimizing the array initialization using techniques like `Array.from()` or `Array.create()`, depending on the JavaScript engine and version. Keep in mind that these alternatives might not provide a significant performance difference in this specific benchmark and would depend on the context and requirements of the application.
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