Function containsDuplicateInstances

Returns true if array contains duplicate instances based on === equality checking.

const o1 = { hello: `there` };
const o2 = { hello: `there` };
containsDuplicateInstances([ o1, o2 ]); // False
containsDuplicateInstances([ o1, o1 ]); // True
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Primitive values are compared by value:

containsDuplicateInstances([ 1, 2, 1 ]); // True
containsDuplicateInstances([ `a`, `b`, `a` ]); // True
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Use containsDuplicateValues if you'd rather compare by value.