Returns whether an equivalent value exists in this collection.
This is a slow operation that visits each value in the collection.
By default, the equality operator is Object.equals
.
There is an analogous implementation provided by Set
, SortedSet
, and
SortedArraySet
, but those collections have an intrisinc order and uniqueness,
so they do not support the second argument, equals
.
This method is also distinct from the has
method provided by maps.
For the purposes of the has
method, an Array
behaves like a List
, even
though the Array
implements get
and set
as if it were a Map
.
var array = [1, 2, 3]; array.has(2); array.has(4);
var set = new List(["One", "TWO", "three"]); set.has("two", function (a, b) { return a.toLowerCase() === b.toLowerCase(); });
Returns whether an entry with the given key exists in a Map
.
Whether an equivalent value exists in this collection.