How to get all items that are both is array A and B and save them in array C? using javascript without using loops

Question

lets say I have

var A = [x, y, z]
var B = [1, 2, z, 3, x]

How can I get items present both in A and B like so

var C = [AB]

Without having to loop through both arrays to check for each iteration

Answer 1

You can use Array.prototype.filter() and Array.prototype.includes() to determine if both arrays contain the same element, Set to remove duplicate elements from resulting array

 var A = ["x", "y", "z"] var B = [1, 2, "z", 3, "x"] var C = [...new Set( [...A, ...B].filter(prop => A.includes(prop) && B.includes(prop))) ]; console.log(C); 

Answer 2

With duplicates:

var C = [...A, ...B]
// Result: C = ["x", "y", "z", 1, 2, "z", 3, "x"]

Without duplicates:

var C = [...A, ...B].filter((el, i, a) => i === a.indexOf(el))
// Result: C = ["x", "y", "z", 1, 2, 3]

Update: if you want the intersection of both arrays:

var C = A.filter(function(n) {
    return B.indexOf(n) !== -1;
});
// Result: C = ["x", "z"]

Answer 3

 let a = new Set(["x", "y", "z"]); let b = new Set([1, 2, "z", 3, "x"]); let intersection = [...a].filter(x => b.has(x)); console.log(intersection); 

Answer 4

Sort each array then merge?

/* sort DESC */
A.sort(function(a,b){ return b-a; })
B.sort(function(a,b){ return b-a; })

then use:

function union_destructive(a, b)
{
  var result = [];
  while( a.length > 0 || b.length > 0 )
  {  
     if      (a[0] > b[0] ){ result.push(a.shift()); }
     else if (a[0] < b[0] ){ result.push(b.shift()); }
     else /* they're equal */
     {
       result.push(a.shift());
       b.shift();
     }
  }

  return result;
}

( Simplest code for array intersection in javascript ):

Thats O(n log n).