[рони]

Вариант )))

function getIntersection(c, d) {
    var a = {};
    c.map(function (b) {
        a[b] = !0
    });
    return a = d.filter(function (b) {
        return a[b]
    })
};
alert( getIntersection([-1,3,-4,5,2,6],[-1,0,8,1,2,9,3,-4,5,7]) )