capnp-js-plugin/lib/context/joinId.js

Capnproto implementation for Javascript

    var zeros = "00000000";
    module.exports = function(id) {
        var hi = id[0].toString(16);
        var lo = id[1].toString(16);
        return "0x" + hi + zeros.substring(0, 8 - lo.length) + lo;
    };