JS to find duplicate elements in two arrays

    const a = [1, 2, 3, 4, 6, 5, 5]
    const b = [5, 6, 7, 8, 5, 6, 9]
    function repeatElement(a, b) {
      let arr1 = []
      for (let i = 0; i < a.length; i++) {
        for (let j = 0; j < b.length; j++) {
          if (a[i] == b[j] && arr1.indexOf(a[i]) == -1) {
            arr1.push(a[i])
          }
        }
      }
      return arr1
    }
    console.log(repeatElement(a, b))

    const a = [1, 2, 3, 4, 6, 5, 5]
    const b = [5, 6, 7, 8, 5, 6, 9]

    function repeatElement1(a, b) {
      let arr = []
      for (let i = 0; i < a.length; i++) {
        if (b.indexOf(a[i]) !== -1 && arr.includes(a[i]) == false) {
          arr.push(a[i])
        }
      }
      return arr
    }
    console.log(repeatElement1(a, b))