Re-writing underscore _.uniq

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//for a sorted array
var iterator = function(value) { return value === 1; };
var numbers = [1, 2, 2, 3, 4, 4];

expect(_.uniq(numbers, true, iterator)).to.eql([1, 2]);

Quick question. I'm writing my own version of _.uniq from the Underscore library. I have one test case that I can't pass simply because I don't understand it. From the above test conditions; how could applying _.uniq produce [1, 2] as the end result? I don't see what it's trying to get me to implement here as that's not even unique in any sense. Any ideas?

underscore.js javascript
1 Answers

The third argument is a function that transforms the values before _.uniq performs comparison.

So your initial array becomes [true, false, false, false, false, false], and _.uniq identifies duplicates based on this transformed array.

Since there are only two unique values - true and false - only two elements are included in the end result.

Alisey_83380
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