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To determine if an array includes an element, we could use the popular
(arr.indexOf(el) !== -1) pattern which exhibits two problems: It fails to
"say what you mean", and also fails for
indexOf uses Strict Equality
Comparison and thus
[NaN].indexOf(NaN) === -1.
method is an ECMAScript 2016 (ES7) proposal. It can be used to determine
whether an array includes a given element in an elegant way.
It compares first arguments to the elements of the array, in ascending order,
using the SameValueZero algorithm
and if found at any position, returns
false is returned.
The optional second argument
fromIndex defaults to
0 (i.e. the whole array is searched). If it is negative, it is
used as the offset from the end of the array to compute