How to associate any javascript event (onmousemove, onclick etc.) using prototype objects

Good people see if you can help me I have a "class" called bar that you pass over a box is created but does not move and I would like to know why

caja=document.getElementById("caja");
        caja.style.width = "800px";
        caja.style.height = "600px";
        caja.style.backgroundColor = "rgb(0, 0, 0)";

        pelota = new Pelota();
        pelota.crearBola();
        //clearInterval(pelota.intervalo);
        raqueta = new Barra();
        raqueta.crearBarra();
        caja.onmousemove=function (elEvento){
            eventoBarra = window.event||elEvento;
            cx = eventoBarra.clientX;
            cy = eventoBarra.clientY;
            console.log("Cliente X "+cx+" Cliente Y "+cy);
            if (cx >= 0 && cx <= parseInt(caja.style.width) - parseInt(raqueta.width)){
                raqueta.left= cx;
                console.log("Valor del ancho de la barra: "+raqueta.left);
                //contLeftBarra = cx;
                //informacionDelJuego();
            }
        } 

function Barra(){
this.width=100;
this.height=20;
this.left=380;
this.top=520;

} Barra.prototype.crearBarra = function (elEvento) {     this.barra = document.createElement ("div"); // we create the bar in the game environment     this.barra.style.height = this.height + "px";     this.barra.style.width = this.width + "px";     this.barra.style.backgroundColor="# 9a0827";     this.barra.style.position="absolute";     this.barra.style.left = this.left + "px";     this.barra.style.top = this.top + "px";     this.barra.style.borderRadius="1em";     caja.appendChild (this.barra);

}