new Array(500)
Array.from({ length: 500 })
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
new Array() | |
Array.from() |
Test name | Executions per second |
---|---|
new Array() | 6366132.5 Ops/sec |
Array.from() | 99618.4 Ops/sec |
Let's break down the provided JSON and explain what's being tested.
Benchmark Definition
The first section defines a benchmark, which is a measure of performance in software development. In this case, we're testing two approaches to create filled arrays:
new Array(n)
Array.from({ length: n })
Both methods aim to create an array with n
elements, filled with a default value (usually undefined
). The main difference lies in the syntax and potential performance implications.
Options Compared
The benchmark compares two options:
A) Using the traditional new Array(n)
method.
B) Using the Array.from()
method with an object initializer.
Pros and Cons of Each Approach
new Array(n)
Array.from()
with an object initializernew Array(n)
for large arrays, as it avoids creating unnecessary objectsArray.from([1, 2], (_, i) => i * 2)
)Other Considerations
The benchmark assumes that the initialization objects are empty ({ length: n }
). This simplifies the comparison and focuses on the creation of filled arrays. If you wanted to compare more complex initialization patterns, the Array.from()
method would provide more flexibility.
Library and Syntax Features
There is no specific library mentioned in this benchmark. However, if we consider Array.from()
, it was introduced in ECMAScript 2015 (ES6) and provides a convenient way to create arrays from iterable sources or objects.
Special JS Feature or Syntax
None are explicitly mentioned in this benchmark. If you wanted to test specific features like async/await, Promises, or Web Workers, you would need to modify the benchmark definition accordingly.
Now, let's discuss alternative approaches:
Array
constructor with a single argument: This method is similar to new Array(n)
, but it avoids creating an unnecessary object. However, it still has performance implications for very large arrays.Array.from()
with a custom iterator: Instead of using an empty object initializer, you could use a custom iterator function to create the array. This approach provides more flexibility and can be useful in specific scenarios.Keep in mind that benchmarking is an essential part of software development, as it helps identify performance bottlenecks and optimize code for different browsers and environments.