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JavaScript concat vs spread 2020
(version: 0)
Comparing performance of:
.concat() vs spread
Created:
5 years ago
by:
Registered User
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Tests:
.concat()
const items = [5, 23] const newItems = [42] const updated = items.concat(newItems)
spread
const items = [5, 23] const newItems = [42] const updated = [...items, ...newItems]
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Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
.concat()
spread
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the JavaScript microbenchmark on MeasureThat.net. **Benchmark Purpose** The benchmark tests two approaches to concatenate (join) arrays in JavaScript: the `.concat()` method and the spread operator (`...`). The goal is to determine which approach is faster, more efficient, or better suited for specific use cases. **Options Compared** Two options are compared: 1. **`.concat()`**: This method takes one or more arrays as arguments and returns a new array that contains all elements from the original arrays. 2. **Spread Operator (`...`)**: This operator allows you to create a new array by spreading the elements of an existing array. **Pros and Cons** * `.concat()`: Pros: + Well-known and widely supported method + Can handle nested arrays + Can be used with other methods, like `Array.prototype.push()` * `.concat()` Pros: + More concise and readable code + Faster execution time due to optimized internal implementation (according to the benchmark) + Can be used with functional programming techniques However, `.concat()` has some drawbacks: * It creates a new array, which can lead to higher memory usage for large datasets. * It's slower than the spread operator in most cases. **Library and Syntax** No external libraries are required for this benchmark. The syntax used is standard JavaScript. The spread operator (`...`) was introduced in ECMAScript 2015 (ES6) as a new way to create arrays from existing arrays or other iterable objects. **Special JS Features or Syntax** There is no special feature or syntax mentioned in the benchmark definition, but it's worth noting that the benchmark uses JavaScript's `const` keyword for variable declarations, which was introduced in ES5. The spread operator (`...`) also relies on the `Symbol.iterator` method, which was introduced in ES3. **Other Alternatives** If you want to compare other methods for concatenating arrays, some alternatives are: 1. **Array.prototype.push()**: This method adds one or more elements to the end of an array and returns the updated array. 2. **Array.prototype.unshift()**: This method adds one or more elements to the beginning of an array and returns the updated array. 3. **`Array.prototype.reduce()` with a callback function**: This method applies a reduction operation to each element in an array and returns the resulting array. These alternatives may have different performance characteristics, syntax, and use cases compared to `.concat()` and the spread operator.
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