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setting array length + assignation vs push
(version: 0)
Comparing performance of:
Set length and assignation vs Push
Created:
3 years ago
by:
Guest
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Tests:
Set length and assignation
var size = 10000; var arr2 = []; arr2.length = size; for (var i = 0; i < size; i++){ arr2[i] = i; }
Push
var size = 10000; var arr3 = []; for (var i = 0; i < size; i++){ arr3.push(i); }
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Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
Set length and assignation
Push
Fastest:
N/A
Slowest:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark and explain what's being tested, compared, and considered. **Benchmark Definition** The benchmark is defined by two test cases: `Set length and assignation` and `Push`. The benchmark measures the performance difference between two approaches to initialize an array of a specific length in JavaScript. **Approaches Compared** 1. **`arr2.length = size;`**: This approach sets the length of the array using the dot notation (`arr2.length = size;`) and then uses a loop to assign values to each element. 2. **`arr3.push(i);`**: This approach uses the `push()` method to add elements to the end of the array, starting with an initial value. **Pros and Cons** * **`arr2.length = size;`**: + Pros: This approach is often considered more efficient because it avoids creating intermediate arrays or objects, which can lead to additional memory allocations. + Cons: It may require more code to set the length explicitly, and if the initial value is not a number (e.g., an object), this approach won't work correctly. * **`arr3.push(i);`**: + Pros: This approach is often considered simpler and more concise, as it directly adds elements to the end of the array without setting its length first. + Cons: It may lead to additional memory allocations if the push method creates new arrays or objects internally. **Library and Special JS Features** None of the benchmark tests use any external libraries or special JavaScript features. The code is self-contained, making it easy for developers to understand and reproduce the test cases. **Other Considerations** When testing array initialization performance, other factors may come into play, such as: * Array type: Testing with different types of arrays (e.g., `Uint8Array`, `Float64Array`) can reveal differences in performance. * Initial value complexity: Using more complex initial values (e.g., objects or functions) can affect the performance of both approaches. * Loop iteration count: Increasing the number of iterations within the loop can impact performance. **Alternatives** Other alternatives for testing array initialization performance might include: * Using `Array.from()` instead of creating arrays using the dot notation or push method * Comparing different methods to create a new array, such as using `slice()`, `concat()`, or spread syntax (`[...array]`) * Testing with larger or smaller array sizes to observe any significant changes in performance
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