has(value, equals?)

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.

On collections


  • has(value)
  • has(value, equals)


var array = [1, 2, 3];
var set = new List(["One", "TWO", "three"]);
set.has("two", function (a, b) {
    return a.toLowerCase() === b.toLowerCase();


  • has(key)

    Returns whether an entry with the given key exists in a Map.

  • has(value)

    Whether an equivalent value exists in this collection.