promise using Q about error propagation

q_error_propagation.js

    var d = Q.defer(),
            ret = [],
            p = d.promise;

    var p2 = p.then(
            function (v) {
                ret.push("e1 :" + v);
                throw "e1";
            },
            function (r) {
                ret.push("e2 :" + r);
                return "e2";
            });

    var p3 = p2.then(
            function (v) {
                ret.push("e3 :" + v);
                throw "e3";
            },
            function (r) {
                ret.push("e4 :" + r);
                return "e4";
            });

    var p4 = p3.then(function (v) {
        ret.push("e5 :" + v);
        throw "e5";
    }, function (r) {
        ret.push("e6 :" + r);
        return "e6";
    });

    setTimeout(function () {
        d.resolve(1);
    }, 100);

    setTimeout(function () {
        alert(ret.join("\n"));
    }, 200);

@yiminghe happy to help! :)