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Array.prototype.concat vs Spread operator
(version: 0)
Compare the new ES6 spread operator with the traditional concat() method on large datasets
Comparing performance of:
Array.prototype.concat vs Spread operator
Created:
8 years ago
by:
Guest
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Tests:
Array.prototype.concat
const test = [].concatArray(10000).fill('1').concat(Array(100).fill('2'));
Spread operator
const test = [ ...Array(10000).fill('1'), ...Array(100).fill('2')];
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Suite status:
<idle, ready to run>
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Test case name
Result
Array.prototype.concat
Spread operator
Fastest:
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Slowest:
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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. The provided benchmark measures the performance difference between two approaches for concatenating arrays in JavaScript: `Array.prototype.concat()` and the new ES6 spread operator (`...`). **Options compared:** 1. **Array.prototype.concat()**: This method creates a new array by copying elements from two or more source arrays. 2. **Spread operator (`...`)**: This operator creates a new array by iterating over an iterable (such as an array) and creating a new element for each iteration. **Pros and Cons of each approach:** 1. **Array.prototype.concat()**: * Pros: + Widely supported in older browsers. + Can be more predictable in terms of performance, since it creates a new array from scratch. * Cons: + Requires an additional method call (`concat()`), which can add overhead. + May perform poorly when dealing with very large arrays, as it needs to create a new array and copy all elements. 2. **Spread operator (`...`)**: * Pros: + More concise and expressive than `Array.prototype.concat()`. + Can take advantage of modern JavaScript optimizations, such as parallel execution of iterations. * Cons: + May not be supported in older browsers or environments that don't understand the spread operator. + Can lead to unexpected behavior if not used carefully (e.g., when concatenating arrays with different lengths). **Library:** None. **Special JavaScript features or syntax:** The benchmark uses ES6 spread syntax (`...`), which is a relatively new feature introduced in ECMAScript 2015. The spread operator allows you to create a new array by iterating over an iterable and creating a new element for each iteration. **Other alternatives:** 1. **Array.prototype.push()**: Instead of concatenating two arrays, you could use `push()` to add elements to the end of one array. 2. **Array.prototype.reduce()**: You could use `reduce()` to concatenate two arrays by accumulating the results in an accumulator variable. 3. **String concatenation**: If you're only dealing with strings, you could concatenate them using the `+` operator or string literals. Keep in mind that these alternatives may not be as efficient or concise as the spread operator or `Array.prototype.concat()`, depending on your specific use case and performance requirements.
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