messageport

The messageport JavaScript object enables passing a JavaScript object as an associative array from JavaScript to BrightScript. This interface works whether the script is executing inside an HTML widget created by BrightScript, an HTML widget created from JavaScript, or a Node.js® instance.

This interface is the preferred way for JavaScript content to communicate with its parent application.

messageport IDL

interface BsMessage {
    attribute String type;
};

callback MessagePortCallback = void (BsMessage event);

interface MessagePort {
    void PostBSMessage(Object message);
    void addEventListener(String type, MessagePortCallback callback);
    void removeEventListener(String type, MessagePortCallback callback);
};

Object Creation

To create a messageport object first load the @brightsign/messageport module using the require() method.

var MESSAGE_PORT = require("@brightsign/messageport");
var bsMessage = new MESSAGE_PORT();

MessagePort

PostBsMessage ()

PostBsMessage(Object message)

Objects passed to PostBSMessage() will be received as events in the parent application:

for HTML widgets created from BrightScript, the parent roHtmlWidget will generate a roHtmlWidgetEvent with reason set to "message"
for HTML widgets created from JavaScript, the parent @brightsign/htmlwidget will generate a "message" event
for Node applications, the parent roNodeJs object will generate a roNodeJsEvent with reason set to "message"

Examples

The following script will send a collection of properties to BrightScript:

function myFunction()
{
    var bsMessage = new require("@brightsign/messageport");
    bsMessage.PostBSMessage({complete: true, result: "PASS"});
}

The message will appear in BrightScript as an roNodeJsEvent. In this case, the GetData().reason equals "message" and GetData().message contains the roAssociativeArray.

while not finished
    ev = mp.WaitMessage(30000)
    if type(ev) <> "roHtmlWidgetEvent" then
        print type(ev)
        stop
    end if
    payload = ev.GetData()
    print payload
    print "Reason: "; payload.reason
    if payload.reason = "message" then
        print "Message: "; payload.message
        if payload.message.complete = invalid then
            stop
        else if payload.message.complete = "true" then
            finished = true
            if payload.message.result = "PASS" then
                print "Test passed"
            else
                print "Test failed: "; payload.message.err
                stop
            end if
        end if
    end if
end while

The following script will display the contents of the event:

var MESSAGE_PORT = require("@brightsign/messageport");
var bsMessage = new MESSAGE_PORT();
 
bsMessage.addEventListener('bsmessage', function(msg) { console.log(JSON.stringify(msg)); })

In BrightScript, the roNodeJs.PostJSMessage() method can be used to post a message to JavaScript:

nodejs.PostJSMessage({ Param1: "Data1", Param2: "Data2", Param3: "Data3" })