To merge two arrays in JavaScript and de-duplicate items, we use the spread operator.
For instance, we write
const array1 = ["foo", "bar"];
const array2 = ["baz", "qux"];
console.log(Array.from(new Set([...array1, ...array2])));
to put all the items in array1 and array2 into a new array with the spread operator.
Then we create a new set from the array with the Set constructor to remove the duplicates.
And then we call Array.from with the set to convert it back to an array.
