How do I empty an array in JavaScript?

Is there a way to empty an array and if so possibly with
.remove()?

For
instance,

A =
            [1,2,3,4];

How can I
empty that?

itemprop="text">

class="normal">Answer

Ways to
clear an existing array
A:

Method
1

(this was my
original answer to the question)

A
            = [];

This code will
set the variable A to a new empty array. This is perfect if you
don't have references to the original array
A anywhere else because this actually creates a
brand new (empty) array. You should be careful with this method because if you have
referenced this array from another variable or property, the original array will remain
unchanged. Only use this if you only reference the array by its original variable
A.

This is also the
fastest solution.

This code sample
shows the issue you can encounter when using this
method:

var arr1 =
            ['a','b','c','d','e','f'];
var arr2 = arr1; // Reference arr1 by another
            variable 
arr1 = [];
console.log(arr2); // Output
            ['a','b','c','d','e','f']

Method
2 (as href="https://stackoverflow.com/a/1234337/113570">suggested by href="https://stackoverflow.com/users/2214/matthew-crumley">Matthew
Crumley)

A.length
            = 0

This will clear
the existing array by setting its length to 0. Some have argued that this may not work
in all implementations of JavaScript, but it turns out that this is not the case. It
also works when using "strict mode" in ECMAScript 5 because the length property of an
array is a read/write
property.

Method 3
(as suggested by
href="https://stackoverflow.com/users/1047275/anthony">Anthony)

A.splice(0,A.length)

Using
.splice() will work perfectly, but since the
.splice() function will return an array with all the removed
items, it will actually return a copy of the original array. Benchmarks suggest that
this has no effect on performance
whatsoever.

Method
4 (as href="https://stackoverflow.com/a/17306971/113570">suggested by href="https://stackoverflow.com/users/990356/tanguy-k">tanguy_k)

while(A.length
            > 0) {

            A.pop();
}

This
solution is not very succinct, and it is also the slowest solution, contrary to earlier
benchmarks referenced in the original
answer.

Performance

Of
all the methods of clearing an existing
array, methods 2 and 3 are very similar in performance and are
a lot faster than method 4. See this rel="noreferrer">benchmark.

As
pointed out by href="https://stackoverflow.com/users/47401/diadistis">Diadistis in their
answer below, the
original benchmarks that were used to determine the performance of the four methods
described above were flawed. The original benchmark reused the cleared array so the
second iteration was clearing an array that was already
empty.

The following benchmark fixes this flaw:
rel="noreferrer">http://jsben.ch/#/hyj65. It clearly shows that methods #2
(length property) and #3 (splice) are the fastest (not counting method #1 which doesn't
change the original array).

/>

This has been a hot topic and the cause
of a lot of controversy. There are actually many correct answers and because this answer
has been marked as the accepted answer for a very long time, I will include all of the
methods here. If you vote for this answer, please upvote the other answers that I have
referenced as well.