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spread vs concat vs unshift 213124
(version: 0)
spread vs concat vs unshift
Comparing performance of:
arrayUnshift123 vs arrayConcat123 vs arraySpread123 vs arrayUnshiftApply
Created:
6 years ago
by:
Guest
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Script Preparation code:
var array = [1,2,3]; var array2 = [-1,-2,-3];
Tests:
arrayUnshift123
array.unshift(...array2);
arrayConcat123
array = array2.concat(array)
arraySpread123
array = [...array2, ...array]
arrayUnshiftApply
array.unshift.apply(array, array2)
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (4)
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Test case name
Result
arrayUnshift123
arrayConcat123
arraySpread123
arrayUnshiftApply
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of JavaScript microbenchmarks! **Benchmark Overview** The provided JSON represents a benchmark that tests the performance of three ways to concatenate or append elements to an array in JavaScript: 1. `unshift()` 2. `concat()` 3. `spread` (using the spread operator, `...`) These methods are commonly used in JavaScript for array manipulation and can have significant performance implications. **Method Comparison** The test cases compare the performance of these three methods: * `array.unshift(...array2)`: This method uses the `unshift()` method to add elements at the beginning of the array. * `array = array2.concat(array)`: This method uses the `concat()` method to create a new array by concatenating `array2` and `array`. * `array = [...array2, ...array]`: This method uses the spread operator (`...`) to create a new array by spreading elements from `array2` and `array`. **Pros and Cons of Each Approach** Here are some pros and cons for each approach: 1. **`unshift()`**: * Pros: Can be more efficient than `concat()` when appending multiple elements, as it only requires a single operation. * Cons: Can be slower than `concat()` for small arrays or when appending a single element. 2. **`concat()`**: * Pros: Generally faster and more reliable than `unshift()`, especially for larger arrays. * Cons: Creates a new array, which can be memory-intensive. 3. **`spread` (using `...`)**: * Pros: Concise and expressive syntax, easy to read and maintain. * Cons: Can be slower than `concat()` due to the overhead of creating a new array. **Library Usage** None of the test cases use any external libraries. **Special JS Features or Syntax** The spread operator (`...`) is used in one of the test cases (`array = [...array2, ...array]`). The spread operator is a relatively recent addition to JavaScript (introduced in ECMAScript 2015) and allows for concise array creation by spreading elements from an existing array. **Other Alternatives** Some alternative approaches to appending elements to an array include: * Using `push()` method: `array.push(...array2)` * Using `slice()` method: `array = [...array.slice(0), ...array2]` * Using `Array.prototype.concat.call()` method: `array = Array.prototype.concat.call(array, array2)` However, these alternatives may not be as efficient or concise as the three methods being tested. I hope this explanation helps!
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