(not implemented) Finds the first value within a collection that passes a test. Finds the first index within a collection that passes a test.
This is a method implemented by some JavaScript engines, but not yet provided by MontageJS Collections nor its Array shims.
This method is defined by an ECMAScript 6 proposal and documented on MDN.
(not implemented) Finds the last index within a collection that passes a test, searching from the right.
(not implemented) Finds the first value within a collection that passes a test.
Finds the first equivalent value.