Find Single Occurring string in JavaScript Array

let myArr = [2, 3, 4, 3, 3, 2, 4, 9, 1, 2, 5, 5];
let a1 = [];
let a2 = [];
// 9,1

// let szArr = myArr.filter((v,i,a) => a.indexOf(v) === i);

myArr.forEach((a) => {
if(a1.indexOf(a) === -1){
a1.push(a);
a2.push(a);
}else {
if(a2.indexOf(a) !== -1){
a2.splice(a2.indexOf(a),1);
}
}
});

// console.log(szArr);
console.log(a1);
console.log(a2);