Some things to do with arrays

1. How to combine multiple dimensional arrays into a one-dimensional array and remove duplicates?

[ [  "380624818","380820351", "661656375"  ],    [  "380624818",   "380820351",  "675814003" ],
  [ "380624818",  "380820351", "696792073" ],  [ "380624818",  "380820351",   "697794627"   ],]

method:

  let brr=[ [  "380624818","380820351", "661656375"  ],    [  "380624818",   "380820351",  "675814003" ],
  [ "380624818",  "380820351", "696792073" ],  [ "380624818",  "380820351",   "697794627"   ],]

let arr =brr.flat()//二维数组转一维数组
        var res = []
        for (var i = 0; i < arr.length; i++) {
          if (res.indexOf(arr[i]) === -1) {//去重
            res.push(arr[i])//添加到res数组中
          }
        }

I’ll add more next time I meet...