Help create JavaScript mixing in Tapestry5?

I am creating a mixin that creates a javascript file when a textbox receives focus.

I'm new to the mixins idea in Tapestry and I'm not sure where to place the original javascript file that I want to run when the textbox gets focus.

Below is an example of my code: Java mixin class:

package asc.mixins;

import org.apache.tapestry5.RenderSupport;
import org.apache.tapestry5.annotations.AfterRender;
import org.apache.tapestry5.annotations.Environmental;
import org.apache.tapestry5.annotations.IncludeJavaScriptLibrary;
import org.apache.tapestry5.annotations.InjectContainer;
import org.apache.tapestry5.corelib.base.AbstractTextField;

@IncludeJavaScriptLibrary("js_dasher_mixin.js")
public class DasherMixin {

@Environmental
private RenderSupport renderSupport;

@InjectContainer
private AbstractTextField field;

@AfterRender
void addScript() {
    this.renderSupport.addScript("new JSDasher('%s');", 
            this.field.getClientId());
 }


}

      

        
        
        
      

    

Mixing Javascript File:

JSDasher = Class.create({

initialize: function(textField) 
{
    this.textField = $(textField);

    this.textField.observe('focus', this.onFocus.bindAsEventListener(this));
},

onFocus: function(event)
{
    //call my javascript init() function
} 
}

      

        
        
        
      

    

the part of my javascript file that I want to run when the textbox gets focus:

var posX, posY;


// Sets up our global variables and dispatches an init request to the server.
function init() {

posX=0;
posY=0;
canvas = document.getElementById("canvas"); 
canvasWidth = canvas.offsetWidth;
canvasHeight = canvas.offsetHeight;
if (canvas.getContext) {   
    ctx = canvas.getContext("2d");
}

canvas.onclick = canvasClicked;
canvas.onmousemove = mouseMoved; 

canvasOffsetX = findPosX(canvas);
canvasOffsetY = findPosY(canvas);

sessID = -1;

sendInitRQ(canvasWidth, canvasHeight);

}

      

        
        
        
      

    

My javascript file is much larger than the above, my question is where should I put the javascript code above?

Should all this be in the mixin.js file? if so, where exactly should he go?

Thanks in advance for your help.