Get the unique values from two arrays and put them in another array [duplicate]

Answer 1

Similar to above but will work with more than two arrays

var array1 = ['12','1','10','19','100'];
var array2 = ['12','10','19'];
var i = 0;
var hist = {};
var array3 = [];

buildhist(array1);
buildhist(array2);

for (i in hist) {
    if (hist[i] === 1) {
        array3.push(i);
    }
}

console.log(array3);

function buildhist(arr) {
    var i;
    for (i = arr.length - 1; i >= 0; i--) {
        if (hist[arr[i]] === undefined) {
            hist[arr[i]] = 0;
        }
        hist[arr[i]]++;
    }
}