Encode an OID. The first two number are encoded specially in the first octet, then the rest are encoded as one octet per number unless the number exceeds 127. If so, it's encoded as several base-127 octets with the high bit set to indicate continuation.
function oidArray(oid) {
    var bytes, i, val;

    // Enforce some minimum requirements on the OID.
    if (oid.length < 2) {
        throw new Error("Minimum OID length is two.");
    } else if (oid[0] > 2) {
        throw new Error("Invalid OID");
    } else if (oid[0] == 0 && oid[1] > 39) {
        throw new Error("Invalid OID");
    } else if (oid[0] == 1 && oid[1] > 39) {
        throw new Error("Invalid OID");
    } else if (oid[0] == 2 && oid[1] > 79) {
        throw new Error("Invalid OID");
    }

    // Calculate the first byte of the encoded OID according to the 'special' rule.
    bytes = [ 40 * oid[0] + oid[1] ];

    // For the rest of the OID, encode each number individually and add the
    // resulting bytes to the buffer.
    for (i = 2; i < oid.length; i++) {
        val = oid[i];
        if (val > 127) {
            bytes = bytes.concat(oidInt(val));
        } else {
            bytes.push(val);
        }
    }

    return bytes;
}