What is the best way to check if a Javascript Array contains any of the elements of another array? [duplicate]

Question

As per question title, I'm using:

Array.prototype.containsAny = function (otherArray) {
  for (let i = 0; i < otherArray.length; i++) 
     if (this.includes(otherArray[i])) 
       return true;

  return false;
};


let a1 =  [3, 5, 9];
let a2 = [4, 5];
a1.containsAny(a2);

Is there a better way?

Array#includes is a O(n) operation compared to Set#has which is O(1) - If you're doing this as a repeated operation, the whitelist should be made into a Set first. — Mulan
– Mulan, Commented Jan 23, 2019 at 16:22

Code Maniac · Accepted Answer · 2019-01-23 16:17:15Z

1

You can use some and includes.

let a1 =  [3, 5, 9];
let a2 = [4, 5];

function containsAny(a1,a2){
  return a1.some(e=> a2.includes(e))
}

console.log(containsAny(a1,a2))
console.log(containsAny(a1, [1,2]))

answered Jan 23, 2019 at 16:17

Code Maniac

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