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new array vs array length
(version: 0)
Comparing performance of:
new array vs length
Created:
5 years ago
by:
Guest
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HTML Preparation code:
<script> var test = [1, 2, 3] </script>
Tests:
new array
test = []
length
test.length = 0
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
new array
length
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'll break down the provided benchmark definition and test cases to explain what's being tested, compared, and analyzed. **What is being tested?** The main goal of this benchmark is to compare the performance difference between two approaches: 1. Creating an empty array using `new Array()`. 2. Accessing the length property of an existing array (`test.length = 0`). These tests aim to measure how long it takes for a JavaScript engine (in this case, Chrome 88) to execute each approach. **Options compared** Two options are being compared: 1. **Creating an empty array**: `new Array()` 2. **Accessing the length property of an existing array**: `test.length = 0` **Pros and Cons:** * Creating an empty array using `new Array()`: * Pros: It creates a new, empty object that can be used as needed. * Cons: In JavaScript, when you create an array with the `Array` constructor, it returns an instance of `Array`, which is a constructor function. This might lead to some overhead due to the need to create a function call. * Accessing the length property of an existing array: * Pros: It's more concise and doesn't require creating a new object or using the `Array` constructor. * Cons: When you use this method, you're accessing a property of an array. This might incur additional overhead due to the need to check whether the value is numeric. **Library and purpose** There are no libraries being used in these tests. The tests only rely on built-in JavaScript functionality. However, there's a library called 'MeasureThat' (not explicitly mentioned but referenced by MeasureThat.net) that provides this functionality. This library seems like an extension for MeasureThat.net to help measure different types of JavaScript code performance. There are no special JS features or syntax being tested in these examples. **Alternative approaches** Other approaches could be tested, such as: * Using `Array.from()` to create an empty array * Creating a new object with the `Object` constructor and then using the `length` property * Using a library like Lodash's `constant()` function to create an empty array These alternatives would likely have similar performance characteristics, but might require additional setup or configuration.
Related benchmarks:
array.splice vs array.length
empty an array in JavaScript - [] vs setting length
new array vs array.length = 0
array.length = 0 vs []
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