This is straightforward to do using the function.bind method, and you can even have the handler directly in your Cell class.
var Cell = WinJS.Class.define(function(number) {
var e = document.createElement("div"); //...and initialize however.
this.element = e;
e.winControl = this;
this.number = number;
this.symbol = "";
//Also consider using pointerDown event here instead of click; might respond quicker
e.addEventListener("click", this._click.bind(this));
}, {
//Instance members
_click: function (e) {
//Your handler. "this" will be the instance of Cell that was clicked
}
});
The this._click function, as you can see, refers to the instance member Cell._click. Calling this function's bind method is how you then specify the exact object to use as "this" inside that method. Without the call to .bind(this), the handler would still be invoked but "this" would be the global context and not the object you care about.