JS求Array的并集、差集

//合并array
    function hebing_array(a,b) {
        for (var i = 0, j = 0, ci, r = {}, c = []; ci = a[i++] || b[j++]; ) {
            if (r[ci]) continue;
            r[ci] = 1;
            c.push(ci);
        }
        return c;
    }

 

//求差集

function chaji_array(arr1,arr2){

    var arr3 = [];

    for (var i = 0; i < arr1.length; i++) {
                        var flag = true;
                        for (var j = 0; j < arr2.length; j++) {
                            if (arr2[j] == arr1[i]) {
                                flag = false;
                            }
                        }
                        if (flag) {
                            arr3.push(arr1[i]);
                        }
                    }

return arr3;

}