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Destructuring array iterator vs array iterator keys
(version: 0)
Comparing performance of:
Array from array iterator keys vs Array from array iterator alone
Created:
2 years ago
by:
Registered User
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Script Preparation code:
var array_length = 30;
Tests:
Array from array iterator keys
const result = [...Array(array_length).keys()].map(x => ({ number: x + 1 }));
Array from array iterator alone
const result = [...Array(array_length)].map(x => ({ number: x + 1 }));
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
Array from array iterator keys
Array from array iterator alone
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 world of JavaScript microbenchmarks on MeasureThat.net. **What is being tested?** The provided benchmark tests two approaches to creating an array of objects from an array of numbers: 1. **Array.from() with array iterator keys**: This approach uses the `Array.from()` method and iterates over the keys of a new array created using `Array(array_length).keys()`. The resulting array is then mapped over to create an array of objects. 2. **Array from array iterator alone**: In this case, the benchmark creates a new array using `Array(array_length)` and maps over it directly. **Comparison of options** Both approaches have their pros and cons: * **Array.from() with array iterator keys**: * Pros: This approach can be more concise and expressive when dealing with arrays that don't have numerical indices. * Cons: It might incur additional overhead due to the iteration over an iterator object, which could potentially lead to slower performance in some cases. * **Array from array iterator alone**: * Pros: This approach avoids the potential overhead of iterating over an iterator object and can be more straightforward when dealing with arrays that have numerical indices. * Cons: It might become less concise or readable when working with non-numerical index arrays. **Library usage** Neither benchmark uses any libraries, as they are built-in JavaScript features. However, if you were to use a library like Lodash (e.g., `_.map()`) to achieve the same results, it would be an alternative approach. **Special JS feature or syntax** The benchmarks utilize a modern JavaScript feature called "template literals" (`x => ({ number: x + 1 })`). This syntax is used to create objects with dynamic values. The template literal syntax allows you to embed expressions inside string literals, creating a concise way to define the object's properties. **Other alternatives** Some other alternative approaches to achieving this result without using `Array.from()` would be: * Using `forEach()`: Create an array of numbers and then use `forEach()` along with the callback function (`(x) => ({ number: x + 1 })`) to create an object. * Using `reduce()`: Similar to `map()`, you could use `reduce()` to create the array of objects. Here's a quick example of how you might achieve this using `forEach()`: ```javascript var array_length = 30; const result = Array(array_length).fill(0).map((x, i) => ({ number: x + i })); ``` And here's an example with `reduce()`, although it would be less efficient than the original approach since you're creating a new array: ```javascript var array_length = 30; const result = Array(array_length).fill(0).reduce((acc, _, i) => ({ number: acc.number + (i + 1) }), {}); ``` Keep in mind that these alternative approaches will likely be less efficient than the original `Array.from()` method and might not provide a clear performance advantage.
Related benchmarks:
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`Array.slice(-1)[0]` vs `Array[Array.length]` for 10000 length
array.prototype.at() vs array[array.length - 1]
slice vs length-1
`array.slice(-1)[0]` vs `array[array.length - 1]`
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