Operator distinct() and its variants are an important type of Filtering operator. This lessons shows how they work and in what cases are they useful.
For people using TypeScript, you have have to import 'rxjs/add/operator/distinct'; Distinct was not included when importing 'rxjs/Rx'; and my build was erroring out.
var result = foo.distinct((x,y) => x.toLowerCase() === y.toLowerCase());
gives: "error: TypeError: y is undefined"
var result = foo.distinct((x) => x.toLowerCase());
Hi Mike. That's correct. We should update the lesson to use a 'keySelector' function, not a 'compare' function.