sending property attributes value to objects from JS ?

Attributes often have getter and setter methods for checking and setting the attribute. In JS, Maxobj objects have a "message" function used to send a message to the object. You could use this for one of the setter methods. If you are unsure of a setter method, you could check the appropriate object reference, or drag the attribute from the inspector into the patcher window to create a message for setting that attribute.

Here is some sample code showing how to get a reference to a Maxobj in the same patch as the js object (in this case a number object) and change the background color to white or black depending on the message sent to js. In this case the attribute is bgcolor.

function black() {
    var myNumber = this.patcher.getnamed("theNumberBox");

    myNumber.message("bgcolor", 0, 0, 0, 1);
}

function white() {
    var myNumber = this.patcher.getnamed("theNumberBox");

    myNumber.message("bgcolor", 1, 1, 1, 1);
}