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Create empty array
(version: 1)
Comparing performance of:
Array.from vs new Array fill vs Spread
Created:
5 years ago
by:
Registered User
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Tests:
Array.from
Array.from({ length: 1000 });
new Array fill
new Array( 1000 ).fill( undefined );
Spread
[... new Array(1000)]
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
Array.from
new Array fill
Spread
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**Benchmark Overview** MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks, comparing different approaches for common use cases. The provided JSON represents the benchmark definition, which includes three test cases: creating an empty array using `Array.from()`, `new Array().fill(undefined)`, and the spread operator `[... new Array(1000)]`. **Test Case Breakdown** 1. **`Array.from({ length: 1000 });`**: This test case creates a new array with 1000 elements, all initialized to `undefined`. The `Array.from()` method is used to create an array from an iterable object (in this case, an empty object with a `length` property). 2. **`new Array( 1000 ).fill( undefined );`**: This test case creates a new array with 1000 elements, all initialized to `undefined`. The `new Array()` constructor is used to create a new array, and the `.fill()` method is used to fill it with the specified value. 3. **`[... new Array(1000)]`**: This test case uses the spread operator to create a new array from an existing one. The `[... ]` syntax creates a new array by spreading the elements of `new Array(1000)`, which are all initialized to `undefined`. **Comparison and Pros/Cons** The three approaches have different characteristics: * **`Array.from()`**: This method is more concise and readable, but it may incur additional overhead due to the need to create an iterable object. On the other hand, it's a modern JavaScript feature that's widely supported. * **`new Array().fill(undefined)`**: This approach is straightforward and efficient, as it uses the `new Array()` constructor and the `.fill()` method directly. However, it may not be as concise or readable as `Array.from()`. * **Spread operator `[... new Array(1000)]`**: This approach is concise and easy to read, but it may incur additional overhead due to the need to create a new array. Pros and cons of each approach: * **`Array.from()`**: + Pros: Concise, readable, modern JavaScript feature. + Cons: May incur additional overhead. * **`new Array().fill(undefined)`**: + Pros: Efficient, straightforward, widely supported. + Cons: Less concise, less readable than `Array.from()`. * **Spread operator `[... new Array(1000)]`**: + Pros: Concise, easy to read. + Cons: May incur additional overhead. **Library and Special Features** There are no libraries mentioned in the provided JSON. However, it's worth noting that JavaScript has a few special features that might be used in microbenchmarks: * **Async/await**: Not present in this benchmark, but it could be used to measure performance of asynchronous code. * **Generators**: Not present in this benchmark, but they could be used to measure performance of iterative algorithms. **Other Alternatives** If you're looking for alternative ways to create an empty array, here are a few options: * Using the `Array()` constructor with no arguments: `new Array()` * Using a loop to create an empty array: `[] = [];` Keep in mind that these approaches may not be as efficient or concise as the ones mentioned earlier.
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