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Array.from() vs new Array() vs [..Array()]
(version: 0)
Testing the difference between creating filled arrays.
Comparing performance of:
new Array() vs Array.from() vs [...Array()]
Created:
3 years ago
by:
Guest
Go to the latest result
Script Preparation code:
var mapfn = (_, index) => { return index * 2 % 10; }
Tests:
new Array()
new Array(500).fill(500).map(mapfn)
Array.from()
Array.from({ length: 500 }, mapfn)
[...Array()]
[...Array(500)].map(mapfn)
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
new Array()
Array.from()
[...Array()]
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
9 months ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36 Edg/141.0.0.0
Browser/OS:
Chrome 141 on Windows
View result in a separate tab
Embed
Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=618940" width="100%" height="500px"></iframe>
new Array()
1.0M/s
[...Array()]
977K/s
Array.from()
78K/s
View exact numbers
Test name
Executions per second
✓
new Array()
1,024,004 Ops/sec
[...Array()]
977,232 Ops/sec
Array.from()
78,492 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of JavaScript microbenchmarks! The provided JSON represents a benchmark test case on MeasureThat.net, which compares three approaches for creating filled arrays: `new Array()`, `Array.from()` and `[...Array()]`. **Options being compared:** 1. **`new Array()`**: Creates an empty array and then fills it with the specified number of elements using the `fill()` method. 2. **`Array.from()`**: Creates a new array from an existing iterable (in this case, an array) by providing a mapping function to transform each element. 3. **`[...Array()]`**: Creates a new array by spreading an empty array and then filling it with the specified number of elements. **Pros and Cons:** 1. **`new Array()`**: * Pros: Generally considered a simple and efficient approach. * Cons: Can be slower than the other two options for large arrays, as it involves creating an intermediate array using `fill()`. 2. **`Array.from()`**: * Pros: Faster and more memory-efficient than `new Array()` for large arrays, since it avoids creating an intermediate array. * Cons: Requires an existing iterable (in this case, an empty array) to be passed as an argument, which can add complexity to the code. 3. **`[...Array()]`**: * Pros: Simple and efficient approach that creates a new array by spreading an empty array. * Cons: May not be as widely supported or well-known as `new Array()`. **Library usage:** None of the options explicitly use any libraries, but they do rely on built-in JavaScript features like `Array.prototype.fill()` and array spread syntax (`[...array]`). **Special JS feature/syntax:** The benchmark test case uses a few special JavaScript features: 1. **Arrow functions**: The `mapfn` variable is defined as an arrow function, which is a concise way to define small anonymous functions. 2. **Template literals**: The `var mapfn = (_, index) => {\r\n return index * 2 % 10;\r\n}` line uses template literals to create a multiline string. **Other alternatives:** If you need to compare the performance of other array creation methods, some alternatives could be: 1. **`Array.from()` with `map()`**: Creating an empty array and then using `map()` to fill it. 2. **`Array.prototype.slice()`**: Using `slice()` to create a shallow copy of an existing array and then filling it with new elements. 3. **`Uint8Array()` or `Int32Array()`**: Using typed arrays to create arrays optimized for specific data types. These alternatives might have different performance characteristics depending on the specific use case and requirements.
Related benchmarks
Array.from() vs new Array().fil() vs [..Array()]
Array.from() vs new Array().map()
Array.from() vs new Array() with index
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