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from vs slice
(version: 4)
Comparing performance of:
from vs slice vs destr vs while copy vs for copy
Created:
8 years ago
by:
Registered User
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Script Preparation code:
var arr = [] for (var i = 0; i < 1000000; i++) { arr.push('') }
Tests:
from
var n = Array.from(arr)
slice
var n2 = arr.slice()
destr
var n3 = [...arr]
while copy
var n4 = [] while(var arr.pop()) { n4.push(v) }
for copy
var n5 = [] for (var g = 0; g <= arr.length; g++ ) { n5.push(arr[g] }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (5)
Previous results
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Test case name
Result
from
slice
destr
while copy
for copy
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. **Benchmark Overview** The benchmark is designed to compare the performance of different approaches to create a copy of an array in JavaScript. The test cases are as follows: 1. `var n = Array.from(arr)` 2. `var n2 = arr.slice()` 3. `var n3 = [...arr]` (also known as the "spread operator" approach) 4. `var n4 = []\r\n\r\nwhile(var arr.pop()) { n4.push(v) }` (also known as the "while copy" approach) 5. `var n5 = []\r\n\r\nfor (var g = 0; g <= arr.length; g++ ) { n5.push(arr[g] }` (also known as the "for copy" approach) **Options Compared** The benchmark compares the performance of five different approaches to create a copy of an array: 1. `Array.from()`: creates a new array from an existing array or iterable. 2. `slice()`: returns a shallow copy of a portion of an array. 3. Spread operator (`...arr`): creates a new array by spreading the elements of an existing array. 4. While loop copy (`while(var arr.pop()) { n4.push(v) }`) 5. For loop copy (`for (var g = 0; g <= arr.length; g++ ) { n5.push(arr[g] }`) **Pros and Cons of Each Approach** 1. `Array.from()`: creates a new array with the same elements as the original array, but may not be suitable for very large arrays due to memory constraints. * Pros: efficient, reliable * Cons: may consume more memory, can be slower for very large arrays 2. `slice()`: returns a shallow copy of a portion of an array. * Pros: fast, efficient, and suitable for most use cases * Cons: may not preserve the original array's properties (e.g., prototype chain) 3. Spread operator (`...arr`): creates a new array by spreading the elements of an existing array. * Pros: modern, concise syntax * Cons: may be slower than `slice()` for very large arrays, can consume more memory 4. While loop copy (`while(var arr.pop()) { n4.push(v) }`): * Pros: simple, no additional library required * Cons: may be slower and less efficient than other approaches, requires manual handling of array elements 5. For loop copy (`for (var g = 0; g <= arr.length; g++ ) { n5.push(arr[g] }`): * Pros: straightforward, simple syntax * Cons: may be slower and less efficient than other approaches, prone to errors due to potential indexing issues **Library Usage** The `Array.from()` method uses the built-in `Array.prototype.from()` function, which is a part of the ECMAScript standard. The `slice()` method also uses a built-in function. **Special JS Feature or Syntax** None of the test cases use any special JavaScript features or syntax beyond what is covered in the ECMAScript standard. **Other Alternatives** If you need to create a copy of an array, there are other alternatives you can consider: * Using `Array.prototype.map()` and then spreading the resulting array using the spread operator (`...`) * Using a library like Lodash's `cloneDeep()` function * Using a data structure like a linked list or a tree instead of an array Keep in mind that each approach has its trade-offs, and the best choice depends on your specific use case and performance requirements.
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