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 can use Object.reduce, Object.entries for this like below

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


let res = Object.entries(
            array.reduce((o, d) => {
              let key = d.join('-')
              o[key] = (o[key] || 0) + 1

              return o
          }, {}))
          .flatMap(([k, v]) => v > 2 ? [k.split('-').map(Number)] : [])
  
  
console.log(res)

OR may be just with Array.filters

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

let temp = {}
let res = array.filter(d => {
  let key = d.join('-')
  temp[key] = (temp[key] || 0) + 1
  
  return temp[key] == 3
})

console.log(res)