How can I detect the distance that the user's mouse has moved?

Question

I'm trying to detect the distance the mouse has moved, in pixels. I am currently using:

$(document).mousemove(function(event) {
    var startingTop = 10,
        startingLeft = 22,
        math = Math.abs(((startingTop - event.clientY) + (startingLeft - event.clientX)) + 14) + 'px';
    $('span').text('From your starting point(22x10) you moved:   ' + math);
});

However, I don't feel like this is the right way to do this, or is it? It doesn't feel to consistent to me.

Here is a demo of how it is working right now: http://jsfiddle.net/Em4Xu/1/

Extra Details:

I'm actually developing a drag & drop plugin and I want to create a feature called distance, like draggable has it, where you have to pull your mouse a certain amount of pixels before it drags. I'm not 100% sure how to do this, so first I need to get the pixels that the mouse has moved from the startingTop and startingLeft position.

Does anyone have any suggestions?

Answer 1

You got your math wrong. Here's improved version: http://jsfiddle.net/stulentsev/Em4Xu/26/

$(document).mousemove(function(event) {
    var startingTop = 10,
        startingLeft = 22,
        math = Math.round(Math.sqrt(Math.pow(startingTop - event.clientY, 2) + 
                                    Math.pow(startingLeft - event.clientX, 2))) + 'px';
    $('span').text('From your starting point(22x10) you moved:   ' + math);
});