Javascript filter an array with matching values

Question

How could I filter and find a number that is repeated 3 times from my array?

function produceChanceNumbers(){
        //initiate array
        var arr = [];
        //begin running 10 times
        for (var i = 0, l = 10; i < l; i++) {
            arr.push(Math.round(Math.random() * 10));
        }
        console.log(arr);
        //inputs array in html element
        document.getElementById("loop").innerHTML = arr.join(" ");
        var winner = 
        //begin filtering but only replaces numbers that repeat
        console.log(arr.filter(function(value, index, array){
            return array.indexOf(value) === index;
        }));

    }//end produceChanceNumbers

html:

<button onClick="produceChanceNumbers()">1</button>

Yes, I feel like im headed in the right direction but don't know how I can make it realize that a certain number was outputted 3 times. — Gianni
– Gianni, Commented Sep 28, 2016 at 0:16
Is this the idea? The triplet-occurrence numbers push 3 times, you can easily tweak it. — Andrew Li
– Andrew Li, Commented Sep 28, 2016 at 0:24
Oh yes actually that your js bin worked perfectly. So it is grabbing that array then just producing another array with the number that matched 3 times. That is really cool. Thank you — Gianni
– Gianni, Commented Sep 28, 2016 at 0:33
make sure to change the condition to be exactly 3, right now it's greater than or equal to 3, and no problem! — Andrew Li
– Andrew Li, Commented Sep 28, 2016 at 0:34

ryanve · Accepted Answer · 2016-09-28 00:43:46Z

4

I'd write a separate function for your filter like

function filterByCount(array, count) {
    return array.filter(function(value) {
        return array.filter(function(v) {
          return v === value
        }).length === count
    })
}

that you could use like

filterByCount([1, 1, 8, 1], 3) // [1, 1, 1]
filterByCount([1, 1, 8, 1], 1) // [8]

edited Sep 28, 2016 at 0:43

answered Sep 28, 2016 at 0:37

ryanve

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1 Comment

Andrew Li Over a year ago

I think the OP is trying to retrieve the number which is repeated 3 times. Regardless, nice answer!

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