Don't add event handlers with inline code.

function AddToPage()
{
    $('#some_item').html("<div id='box'></div>");
    $('#box').click(this.OnClick);
}

EDIT:

Another way (avoids the extra select):

function AddToPage()
{
    var div = $('<div id="box"></div>'); // probably don't need ID anymore..
    div.click(this.OnClick);
    
    $('#some_item').append(div);
}

EDIT (in response to "how to pass parameters");

I'm not sure what params you want to pass, but..

function AddToPage()
{
    var self = this, div = $('<div></div>');
    div.click(function (eventObj) {
        self.OnClick(eventObj, your, params, here);
    });
    
    $('#some_item').append(div);
}

Don't add event handlers with inline code.

function AddToPage()
{
    $('#some_item').html("<div id='box'></div>");
    $('#box').click(this.OnClick);
}

EDIT:

Another way (avoids the extra select):

function AddToPage()
{
    var div = $('<div id="box"></div>'); // probably don't need ID anymore..
    div.click(this.OnClick);
    
    $('#some_item').append(div);
}

EDIT (in response to "how to pass parameters");

I'm not sure what params you want to pass, but..

function AddToPage()
{
    var self = this, div = $('<div></div>');
    div.click(function (eventObj) {
        self.OnClick(eventObj, your, params, here);
    });
    
    $('#some_item').append(div);
}

Don't add event handlers with inline code.

function AddToPage()
{
    $('#some_item').html("<div id='box'></div>");
    $('#box').click(this.OnClick);
}

EDIT:

Another way (avoids the extra select):

function AddToPage()
{
    var div = $('<div id="box"></div>'); // probably don't need ID anymore..
    div.click(this.OnClick);
    
    $('#some_item').append(div);
}

Don't add event handlers with inline code.

function AddToPage()
{
    $('#some_item').html("<div id='box'></div>");
    $('#box').click(this.OnClick);
}

EDIT:

Another way (avoids the extra select):

function AddToPage()
{
    var div = $('<div id="box"></div>'); // probably don't need ID anymore..
    div.click(this.OnClick);
    
    $('#some_item').append(div);
}

EDIT (in response to "how to pass parameters");

I'm not sure what params you want to pass, but..

function AddToPage()
{
    var self = this, div = $('<div></div>');
    div.click(function (eventObj) {
        self.OnClick(eventObj, your, params, here);
    });
    
    $('#some_item').append(div);
}