Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

Javascript - Track mouse position

Tags:

javascript

People also ask

How can I track my mouse position?

To track the mouse position, we have to find its x-axis (horizontal position) and y-axis (vertical position) inside the browser's tab. You might be aware that the top-left corner of the browser is represented with (0,0) .

Can Javascript move the mouse?

Before we start, you need to know that it's not actually possible to move the mouse pointer to a position using Javascript, such functionality can we easily misused but we can simulate something similar. In this article, we will learn to move the mouse pointer from one pointer to another pointer.


The mouse's position is reported on the event object received by a handler for the mousemove event, which you can attach to the window (the event bubbles):

(function() {
    document.onmousemove = handleMouseMove;
    function handleMouseMove(event) {
        var eventDoc, doc, body;

        event = event || window.event; // IE-ism

        // If pageX/Y aren't available and clientX/Y are,
        // calculate pageX/Y - logic taken from jQuery.
        // (This is to support old IE)
        if (event.pageX == null && event.clientX != null) {
            eventDoc = (event.target && event.target.ownerDocument) || document;
            doc = eventDoc.documentElement;
            body = eventDoc.body;

            event.pageX = event.clientX +
              (doc && doc.scrollLeft || body && body.scrollLeft || 0) -
              (doc && doc.clientLeft || body && body.clientLeft || 0);
            event.pageY = event.clientY +
              (doc && doc.scrollTop  || body && body.scrollTop  || 0) -
              (doc && doc.clientTop  || body && body.clientTop  || 0 );
        }

        // Use event.pageX / event.pageY here
    }
})();

(Note that the body of that if will only run on old IE.)

Example of the above in action - it draws dots as you drag your mouse over the page. (Tested on IE8, IE11, Firefox 30, Chrome 38.)

If you really need a timer-based solution, you combine this with some state variables:

(function() {
    var mousePos;

    document.onmousemove = handleMouseMove;
    setInterval(getMousePosition, 100); // setInterval repeats every X ms

    function handleMouseMove(event) {
        var dot, eventDoc, doc, body, pageX, pageY;

        event = event || window.event; // IE-ism

        // If pageX/Y aren't available and clientX/Y are,
        // calculate pageX/Y - logic taken from jQuery.
        // (This is to support old IE)
        if (event.pageX == null && event.clientX != null) {
            eventDoc = (event.target && event.target.ownerDocument) || document;
            doc = eventDoc.documentElement;
            body = eventDoc.body;

            event.pageX = event.clientX +
              (doc && doc.scrollLeft || body && body.scrollLeft || 0) -
              (doc && doc.clientLeft || body && body.clientLeft || 0);
            event.pageY = event.clientY +
              (doc && doc.scrollTop  || body && body.scrollTop  || 0) -
              (doc && doc.clientTop  || body && body.clientTop  || 0 );
        }

        mousePos = {
            x: event.pageX,
            y: event.pageY
        };
    }
    function getMousePosition() {
        var pos = mousePos;
        if (!pos) {
            // We haven't seen any movement yet
        }
        else {
            // Use pos.x and pos.y
        }
    }
})();

As far as I'm aware, you can't get the mouse position without having seen an event, something which this answer to another Stack Overflow question seems to confirm.

Side note: If you're going to do something every 100ms (10 times/second), try to keep the actual processing you do in that function very, very limited. That's a lot of work for the browser, particularly older Microsoft ones. Yes, on modern computers it doesn't seem like much, but there is a lot going on in browsers... So for example, you might keep track of the last position you processed and bail from the handler immediately if the position hasn't changed.


onmousemove = function(e){console.log("mouse location:", e.clientX, e.clientY)}

Open your console (Ctrl+Shift+J), copy-paste the code above and move your mouse on browser window.


Here's a solution, based on jQuery and a mouse event listener (which is far better than a regular polling) on the body:

$("body").mousemove(function(e) {
    document.Form1.posx.value = e.pageX;
    document.Form1.posy.value = e.pageY;
})

I believe that we are overthinking this,

function mouse_position(e)
{
//do stuff
}
<body onmousemove="mouse_position(event)"></body>