var params = [ "hello", true, 7 ];
var other = [ 1, 2 ].slice();
var params = [ "hello", true, 7 ]
var other = [ params ]
var params = [ "hello", true, 7 ]
var other = [];
for (i = 0; i < 3; i++) {
other[i] = params[i];
}
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
Array.prototype.slice | |
spread operator | |
copy |
Test name | Executions per second |
---|---|
Array.prototype.slice | 233041392.0 Ops/sec |
spread operator | 130726608.0 Ops/sec |
copy | 83076456.0 Ops/sec |
Let's dive into the world of JavaScript microbenchmarks.
What is being tested?
The provided JSON represents a benchmark comparison between three approaches to create a copy of an array in JavaScript:
Array.prototype.slice()
[ ...params ]
)for
loopThese three approaches are compared to determine which one is the most efficient.
Options compared:
Array.prototype.slice()
: A traditional method to create a copy of an array, which creates a new array and copies the elements from the original array.[ ...params ]
): A newer method introduced in ES6 that uses destructuring syntax to create a new array with the elements of the original array.for
loop: This approach involves looping through the original array and assigning each element to a new location, typically using an array or object.Pros and cons of each approach:
[ ...params ]
):slice()
for
loop:slice()
Libraries and their purpose:
None of the provided benchmark definitions use a specific library, but they do rely on built-in JavaScript features.
Special JS feature or syntax:
The spread operator ([ ...params ]
) is a newer JavaScript feature introduced in ES6. It allows for concise array creation using destructuring syntax.
Other alternatives:
In addition to the three approaches mentioned, there are other ways to create an array copy in JavaScript:
Array.prototype.concat()
: Creates a new array and concatenates the elements of the original array.Object.assign()
: Copies properties from an object into a new object.JSON.parse(JSON.stringify(obj))
: Creates a deep copy of an object by parsing its JSON representation.However, these alternatives are not directly comparable to the three approaches mentioned in this benchmark.