code: function ld(array1, array2, equalFn){
    var n = array1.length;
    var m = array2.length;
    var equalFn = equalFn || equals;
    var matrix = [];
    for(var i = 0; i <= n; i++){
      matrix.push([i]);
    }
    for(var j=1;j<=m;j++){
      matrix[0][j]=j;
    }
    for(var i = 1; i <= n; i++){
      for(var j = 1; j <= m; j++){
        if(equalFn(array1[i-1], array2[j-1])){
          matrix[i][j] = matrix[i-1][j-1];
        }else{
          matrix[i][j] = Math.min(
            matrix[i-1][j]+1, //delete
            matrix[i][j-1]+1//add
            )
        }
      }
    }
    return matrix;
  }
docs: array1 - old array array2 - new array