var arr = [], last = 0
arr.unshift(42); last = arr[0]
arr.push(42); last = arr[arr.length - 1]
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
.unshift() | |
.push() |
Test name | Executions per second |
---|---|
.unshift() | 25940.2 Ops/sec |
.push() | 412210.2 Ops/sec |
Benchmark Explanation
The provided benchmark measures the performance difference between two approaches: arr.unshift()
and arr.push()
, with a reference to the last element in the array.
Options Compared
Two options are compared:
arr.unshift(42); last = arr[0]
: This approach uses the unshift()
method to add an element to the beginning of the array, followed by assigning the value at index 0 (which is now the first element) to a variable named last
.arr.push(42); last = arr[arr.length - 1]
: This approach uses the push()
method to add an element to the end of the array, followed by assigning the value at the last index (i.e., arr.length - 1
) to a variable named last
.Pros and Cons
arr.unshift()
:
Pros:
Cons:
arr.push()
:
Pros:
unshift()
for large arrays or when elements are added frequently to the end.unshift()
.Cons:
Library and Syntax Considerations
In this benchmark, there is no explicit library used. However, it's worth noting that JavaScript's array methods, including push()
and unshift()
, are part of the language itself.
There are no special JavaScript features or syntax used in this benchmark.
Alternatives
Other alternatives to compare performance include:
[]
vs new Array(size)
: This would measure the performance difference between creating an array from scratch using the literal syntax versus using the new
keyword.Array.prototype.push()
vs push()
: This would measure the performance difference between calling the method on the prototype chain (i.e., arr.push()
) versus on the instance itself (i.e., arr.push()
).Array.prototype.unshift()
vs unshift()
: This would measure the performance difference between calling the method on the prototype chain (i.e., arr.unshift()
) versus on the instance itself (i.e., arr.unshift()
).These alternative benchmarks would provide more comprehensive insights into JavaScript array operations and their performance characteristics.