How to compare an array to an array of arrays?

Question

This is an attempt in a tic tac toe game app. I have two arrays playerMoves and winningCombinations . Like this.

var playerMoves= [0,1,4];
var winningCombinations = [
        [0,1,2],[3,4,5],[6,7,8],
        [0,3,6],[1,4,7],[2,5,8],
        [0,4,8],[2,4,6]
      ];

I need to filter the winningCombination array such that at-least and at-most two values of playerMoves array matches with each array in winningCombination .

findPossibleMove(playerMoves);
// should return [[0,1,2],[1,4,7], [0,4,8] ]

My attempt

function findPossibleMove(arr){
  var found = 0;
  return arr.forEach((item)=>{
    winningCombinations.map((obj)=>{
      if(obj.indexOf(item) !== -1) {
        found++;
      }
      if(found===2){
        return obj;
      }        
    })
  })      
}

Answer 1

Three simple steps:

• Use indexOf function to check, if specified element from the subarray of winningCombinations array is present in the playerMoves array.
• If so - filter it out with Array#filter function.
• If the returned, filtered subarray has length equal to 2 , it means that two (no more, nor less) elements have appeared - it fulfills our condition - filter it once again with yet another Array#filter .

 let playerMoves = [0, 1, 4]; let winningCombinations = [ [0, 1, 2], [3, 4, 5], [6, 7, 8], [0, 3, 6], [1, 4, 7], [2, 5, 8], [0, 4, 8], [2, 4, 6], ]; let res = winningCombinations.filter(v => v.filter(c => { return playerMoves.indexOf(c) > -1; }).length == 2); console.log(JSON.stringify(res)); 

Answer 2

You can use filter and includes to achieve that:

 var playerMoves= [0,1,4]; var winningCombinations = [ [0,1,2],[3,4,5],[6,7,8], [0,3,6],[1,4,7],[2,5,8], [0,4,8],[2,4,6] ]; var filteredCombinations = winningCombinations.filter((combination) => combination.filter(x => playerMoves.includes(x)).length === 2); console.log(filteredCombinations); 

Answer 3

since we have to check with the length (matched item) in each filtered array, how about skipping creation of filtered array against array and reducing it to a number of matched element and check directly with that instead of the length ?

 let playerMoves = [0, 1, 4]; let winningCombinations = [ [0, 1, 2], [3, 4, 5], [6, 7, 8], [0, 3, 6], [1, 4, 7], [2, 5, 8], [0, 4, 8], [2, 4, 6], ]; let res = winningCombinations.filter(a=> a.reduce((r, v) => r + playerMoves.includes(v), 0)==2); console.log('matching array: ', res)