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Array slice vs for loop (set by index)
(version: 0)
Comparing performance of:
slice vs push
Created:
2 years ago
by:
Guest
Jump to the latest result
Script Preparation code:
var data = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0];
Tests:
slice
var copy = data.slice(3, 8);
push
var copy = []; for (var i = 3; i < 8; i++) { copy[i] = data[i]; }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
slice
push
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.1:latest
, generated one year ago):
Let's dive into the explanation. **What is being tested?** The benchmark compares two different ways of copying an array in JavaScript: using the `slice()` method and using a traditional `for` loop with push operations. **Test Case 1: Using slice()** * **Benchmark Definition**: `var copy = data.slice(3, 8);` * **Library/Feature**: None * **Description**: This test case uses the `slice()` method to create a new array (`copy`) that contains elements from index 3 to index 7 of the original array (`data`). + **Pros**: The `slice()` method is concise and easy to read. + **Cons**: Creating an entirely new array can be memory-intensive for large datasets. **Test Case 2: Using a traditional for loop** * **Benchmark Definition**: `var copy = []; for (var i = 3; i < 8; i++) { copy[i] = data[i]; }` * **Library/Feature**: None * **Description**: This test case uses a traditional `for` loop to iterate over the elements of the original array (`data`) and push them into a new array (`copy`), starting from index 3 to index 7. + **Pros**: The `push()` method can be more memory-efficient than creating an entirely new array, especially for large datasets. + **Cons**: This approach is less concise than using the `slice()` method and may be harder to read. **Other alternatives?** Yes! There are other ways to copy arrays in JavaScript. Some options include: * Using the spread operator (`[...data]`, `[...data.slice(3, 8)]`): Creates a new array with all elements of the original array or a subset thereof. * Using `Array.from()` (ES6+): Converts an iterable into an array. Keep in mind that these alternatives might have their own performance implications and use cases. **What do the results mean?** The latest benchmark result shows that using the `slice()` method (`TestName`: "slice") is significantly faster than using a traditional `for` loop with push operations (`TestName`: "push") on this particular device platform (Chrome Mobile 117, Android). The execution speed per second is approximately 4-5 times higher for the `slice()` method. However, it's essential to note that performance results can vary depending on the specific use case, device, and JavaScript engine. These findings should not be taken as a definitive answer but rather as an indication of the relative performance differences between these two approaches.
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