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Array.from() vs Array()
(version: 0)
Testing the difference between creating filled arrays.
Comparing performance of:
new Array() vs Array.from()
Created:
2 years ago
by:
Guest
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Tests:
new Array()
Array(500).fill({ test: "123", })
Array.from()
Array.from({ length: 500 }, () => ({ test: "123" }))
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Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
new Array()
Array.from()
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the explanation of the provided benchmark. **What is being tested?** The benchmark compares two approaches to create filled arrays in JavaScript: `new Array()` and `Array.from()`. The test case creates an array with 500 elements, each containing a single property `test` with value `"123"`. **Options compared:** Two options are being compared: 1. **`new Array()`**: This approach creates a new array using the constructor function `Array()`, specifying the length of the array as 500. The array is then filled with elements, each containing a single property `test`. 2. **`Array.from()`**: This approach uses the `from()` method to create an array from an iterable source, in this case, an arrow function that generates 500 elements. **Pros and Cons:** **`new Array()`**: Pros: * Simple and straightforward approach * No dependencies on external libraries Cons: * Can be slower than `Array.from()` due to the need to create a new array object using the constructor function * May not be optimized for performance, especially for large arrays **`Array.from()`**: Pros: * More efficient and faster than `new Array()`, as it leverages the optimized `from()` method under the hood * Can handle more complex iterable sources, such as arrays or strings Cons: * Requires a dependency on the `Array.prototype.from()` method, which may not be available in older browsers * May have slightly higher memory overhead due to the creation of an intermediate array object **Other considerations:** The test cases use JavaScript's `length` property and object literal syntax (e.g., `{\r\n\ttest: "123"\r\n}`). These features are widely supported across modern browsers and versions of JavaScript. **Library usage:** No external libraries are required for this benchmark, as it only uses built-in JavaScript features. **Special JS feature or syntax:** The test cases use the arrow function (`() => ({...})`) to generate the iterable source for `Array.from()`. This is a modern JavaScript feature that was introduced in ECMAScript 2015 (ES6). In summary, this benchmark compares two approaches to create filled arrays in JavaScript, highlighting the trade-offs between simplicity and performance. While `new Array()` is straightforward but may be slower, `Array.from()` is more efficient but requires a dependency on the optimized `from()` method.
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