Find if two arrays are repeated in array and then select them

Question

I have multiple arrays in a main/parent array like this:

var array = [[1, 17], [1, 17], [1, 17], [2, 12], [5, 9], [2, 12], [6, 2], [2, 12]];

<

Answer 1

You could take a Map with stringified arrays and count, then filter by count and restore the arrays.

var array = [[1, 17], [1, 17], [1, 17], [2, 12], [5, 9], [2, 12], [6, 2], [2, 12]],
    result = Array
        .from(array.reduce(
            (map, array) =>
                (json => map.set(json, (map.get(json) || 0) + 1))
                (JSON.stringify(array)),
            new Map
         ))
        .filter(([, count]) => count > 2)
        .map(([json]) => JSON.parse(json));
        
console.log(result);

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Filter with a map at wanted count.

var array = [[1, 17], [1, 17], [1, 17], [2, 12], [5, 9], [2, 12], [6, 2], [2, 12]],
    result = array.filter(
        (map => a => 
            (json =>
                (count => map.set(json, count) && !(2 - count))
                (1 + map.get(json) || 1)
            )
            (JSON.stringify(a))
        )
        (new Map)
    );
        
console.log(result);

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Unique!

var array = [[1, 17], [1, 17], [1, 17], [2, 12], [5, 9], [2, 12], [6, 2], [2, 12]],
    result = array.filter(
        (s => a => (j => !s.has(j) && s.add(j))(JSON.stringify(a)))
        (new Set)
    );
        
console.log(result);

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