javascript union array of objects

union

function checkIdentical(o1, o2, properties){
    var identical = false;
    for (var k = 0; k < properties.length; k++) {
        var cp = properties[k];
        if (o1[cp] == o2[cp]) {
            identical = true;
        }
        else {
            identical = false;
            break;
        }
    }

    return identical
}

function unyon(arr1, arr2, properties) {
    var res = arr1.concat(arr2);
    
    for (var i = 0; i < res.length; i++) {
        for (var j = i + 1; j < res.length; j++) {
            
            var identical = checkIdentical(res[i], res[j], properties);
            
            if (identical) {
                res.splice(i, 1);
                j -= 1; // add this
            }

        }
    }
    
    return res;
}

var s1 = [{ x: 1, y: 2 }, { x: 2, y: 2 }];
var s2 = [{ x: 2, y: 1 }, { x: 2, y: 2 }];

var test1 = unyon(s1, s2, ['x', 'y']);
var test2 = unyon(s1, s2, ['x']);