Wikitude Passing value from java to JavaScript to use it in AR.RelativeLocation

I passed an integer from java to javascript, and now I want to use the value to change the altitude of an object.

I added a to RelativeLoction var location = new AR.RelativeLocation(null, 8, 0, a);

The problem is it ignores the value that I passed which is 10 and take a as 0. I know that the value passed correctly from this var e = document.getElementById('loadingMessage').innerHTML = "Altitude: " + a; which shows Altitude: 10.

Javascript code:

var World = {
    loaded: false,
    rotating: false,

    init: function initFn() {
        this.createModelAtLocation();
    },



    createModelAtLocation: function createModelAtLocationFn() {

        /*
            First a location where the model should be displayed will be defined. This location will be relativ to the user.
        */
        var location = new AR.RelativeLocation(null, 8, 0, a);

        /*
            Next the model object is loaded.
        */
        var modelArrow = new AR.Model("assets/arrow.wt3", {
                    onLoaded: this.worldLoaded,
                    scale: {
                        x: 0.005,
                        y: 0.005,
                        z: 0.003
                    },
                    rotate: {
                                    x: 0.0,
                                    y: 90.0,
                                    z: 0.0
                                  },
                                  translate: {
                                      x: 0,
                                      y: 0,
                                      z: 0
                                    }

                });



        var indicatorImage = new AR.ImageResource("assets/indi.png");

        var indicatorDrawable = new AR.ImageDrawable(indicatorImage, 0.1, {
            verticalAnchor: AR.CONST.VERTICAL_ANCHOR.TOP
        });

        /*
            Putting it all together the location and 3D model is added to an AR.GeoObject.
        */
        var obj = new AR.GeoObject(location, {
            drawables: {
               cam: [modelArrow],
               indicator: [indicatorDrawable]
            }
        });
    },

    worldLoaded: function worldLoadedFn() {
        World.loaded = true;
        var e = document.getElementById('loadingMessage').innerHTML = "Altitude: " + a;
        e.parentElement.removeChild(e);
    }
};

    var a = 0;
    var altitude = 0;

       function setAltitude(altitude){
               a = altitude;
           }

World.init();

Edit after Alex's answer:

Now the object and the altitude are not showing not sure if I'm missing something

var World = {
    location: null,
    loaded: false,
    rotating: false,

    init: function initFn() {
        this.createModelAtLocation();
    },

    createModelAtLocation: function createModelAtLocationFn() {

        /*

            First a location where the model should be displayed will be defined. This location will be relativ to the user.
        */
        //var location = new AR.RelativeLocation(null, 8, 0, a);
        World.location = new AR.RelativeLocation(null, 8, 0, a);

        /*
            Next the model object is loaded.
        */
        var modelArrow = new AR.Model("assets/arrow.wt3", {
                    onLoaded: this.worldLoaded,
                    scale: {
                        x: 0.005,
                        y: 0.005,
                        z: 0.003
                    },
                    rotate: {
                                    x: 0.0,
                                    y: 90.0,
                                    z: 0.0
                                  },
                                  translate: {
                                      x: 0,
                                      y: 0,
                                      z: 0
                                    }

                });



        var indicatorImage = new AR.ImageResource("assets/indi.png");

        var indicatorDrawable = new AR.ImageDrawable(indicatorImage, 0.1, {
            verticalAnchor: AR.CONST.VERTICAL_ANCHOR.TOP
        });

        /*
            Putting it all together the location and 3D model is added to an AR.GeoObject.
        */
        var obj = new AR.GeoObject(location, {
            drawables: {
               cam: [modelArrow],
               indicator: [indicatorDrawable]
            }
        });
    },

    worldLoaded: function worldLoadedFn() {
        World.loaded = true;
        var e = document.getElementById('loadingMessage').innerHTML = "Altitude: " + a;
        e.parentElement.removeChild(e);
    }
};
    var a = 0;
    var altitude = 0;

       function setAltitude(altitude){
               //a = altitude;
               //World.location.altitudeDelta  = altitude;
               World.location.a = altitude;
           }

World.init();

I managed to fix the problem here is the answer if anyone is interested

var World = {
    //location: null,
    loaded: false,
    rotating: false,

    loadValuesFromJava: function loadValuesFromJavaFn(Altitude){
        a = Altitude;
        this.createModelAtLocation();
    },

    /*init: function initFn() {
        this.createModelAtLocation();
    },*/

    createModelAtLocation: function createModelAtLocationFn() {

        /*

            First a location where the model should be displayed will be defined. This location will be relativ to the user.
        */
        var location = new AR.RelativeLocation(null, 8, 0, a);
        //World.location = new AR.RelativeLocation(null, 8, 0, a);

        /*
            Next the model object is loaded.
        */
        var modelArrow = new AR.Model("assets/arrow.wt3", {
                    onLoaded: this.worldLoaded,
                    scale: {
                        x: 0.005,
                        y: 0.005,
                        z: 0.003
                    },
                    rotate: {
                                    x: 0.0,
                                    y: 90.0,
                                    z: 0.0
                                  },
                                  translate: {
                                      x: 0,
                                      y: 0,
                                      z: 0
                                    }

                });



        var indicatorImage = new AR.ImageResource("assets/indi.png");

        var indicatorDrawable = new AR.ImageDrawable(indicatorImage, 0.1, {
            verticalAnchor: AR.CONST.VERTICAL_ANCHOR.TOP
        });

        /*
            Putting it all together the location and 3D model is added to an AR.GeoObject.
        */
        var obj = new AR.GeoObject(location, {
            drawables: {
               cam: [modelArrow],
               indicator: [indicatorDrawable]
            }
        });
    },



    worldLoaded: function worldLoadedFn() {
        World.loaded = true;
        var e = document.getElementById('loadingMessage').innerHTML = "Altitude: " + a;
        e.parentElement.removeChild(e);
    }
};

var a = 0;
var Altitude = 0;
    /*var a = 0;
    var altitude = 0;

      function setAltitude(altitude){
               a = altitude;
               //World.location.altitudeDelta  = altitude;
               //World.location.altitudeDelta = altitude;
           }*/

//World.init();
//World.loadValuesFromJava();