Selected text event trigger in Javascript

Here's a quick mashup:

$('div').mouseup(function() {
    var text=getSelectedText();
    if (text!='') alert(text);
});

function getSelectedText() {
    if (window.getSelection) {
        return window.getSelection().toString();
    } else if (document.selection) {
        return document.selection.createRange().text;
    }
    return '';
}​

<div>Here is some text</div>

Demo: http://jsfiddle.net/FvnPS/11/

There is no "Text was selected" (DOM) event, but you can bind a mouseup event to the document.body. Within that event handler, you might just check the

document.selection.createRange().text

or

window.getSelection()

methods. There are several topics on Stackoverflow, like this one javascript to get paragraph of selected text in web page.

I'm not sure what you mean with "finding the position", but to stay in my example world you could use the event propertys for X+Y mouse positions.

Example: http://www.jsfiddle.net/2C6fB/1/