Returns the position of a value, or -1 if the value is not found.
Returns the position of the first of equivalent values. The second argument is an optional index from which to start seeking, and defaults to 0, meaning search the entire collection.
For arrays, equivalence is defined by the === operator.
For all other collections, equivalence is defined by contentEquals, which
can be overridden with an argument to the collection’s constructor, or by
assigning a property to either the instance or prototype.
The default contentEquals is Object.equals, which performs a deep equality
comparison.
This method is slow, requiring a linear walk.
Fast implementations of indexOf(value) exist for SortedSet, SortedArray,
and SortedArraySet, but do not support a start index.
The precedent for the indexOf method is the JavaScript Array method, as
described on MDN.
Returns the last position of a value, or -1 if the value is not found.
Returns the position of a value, or -1 if the value is not found.
(not implemented) Finds the first value within a collection that passes a test. Finds the first index within a collection that passes a test.
Finds the first equivalent value.