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pre fill array
(version: 0)
Comparing performance of:
pre vs non
Created:
4 years ago
by:
Guest
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Script Preparation code:
const n = 10;
Tests:
pre
const n = 10; const arr = new Array(n).fill(0); for (let i = 0; i < n; i++) { arr[i] = i; }
non
const n = 10; const arr = []; for (let i = 0; i < n; i++) { arr.push(i); }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
pre
non
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'd be happy to explain the benchmark test. **Overview** The test measures how fast JavaScript can create and populate an array using two different approaches: creating an empty array and then pushing elements, or creating an array with a specified length and filling it with zeros. **Options Compared** Two options are compared: 1. **"pre"**: Creates an array of length `n` using the `new Array(n).fill(0)` method, followed by a loop to populate each element. 2. **"non"**: Creates an empty array `[]`, then pushes elements into it using a loop. **Pros and Cons** * **"pre"`: + Pros: Can be faster for larger arrays since it avoids the overhead of creating an empty array and pushing elements individually. The `new Array(n).fill(0)` method creates a contiguous block of zeros, which can be more efficient. + Cons: Requires more memory allocation and may have performance differences due to the specifics of the JavaScript engine. * **"non"`: + Pros: More straightforward and simple implementation, avoiding the overhead of creating an array with a specific length. + Cons: Can be slower for larger arrays since it involves pushing elements individually. **Library Used** None. The test does not use any external libraries. **Special JavaScript Features or Syntax** The test uses the `fill()` method to populate the array with zeros, which is a modern JavaScript feature introduced in ECMAScript 5 (ES5). This feature is widely supported across modern browsers and JavaScript engines. **Other Considerations** Other considerations include: * **Array length**: The size of the array being created (`n`) has a significant impact on performance. Larger arrays are more likely to favor the "pre" approach. * **JavaScript Engine**: Different JavaScript engines, such as V8 (used by Chrome), SpiderMonkey (used by Firefox), and Safari's JavaScript engine, may optimize or implement the `new Array(n).fill(0)` method differently, affecting performance. * **Cache Performance**: The test assumes a certain level of cache efficiency for modern browsers. However, in some cases, caching may not be sufficient to make a difference between the two approaches. **Alternatives** Other alternatives to these approaches could include: * Using `Array.prototype.map()` or `Array.prototype.slice()` to create and populate an array. * Utilizing Web Workers or other parallel processing techniques for performance-critical code. * Optimizing array creation using techniques like chunking or caching.
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