How do I find the cursor position within an element in javascript

Question

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Been stuck on this for a while. I can find the cursor position on a mouse move like this:

JavaScript

function myMoveFunction()
{
   document.getElementById("ImageCaption").innerHTML = "Coords: " + event.x + ", " + event.y ;
}

ASP.NET

<asp:ImageButton id="imagebutton1" runat="server" Width="512" Height="262"
                    ImageUrl="DrawRoom.aspx?v=0"
                    OnClick="ImageButton_Click"
                    onmousemove="myMoveFunction()"  />
<p><span id="ImageCaption"></span></p>

And this gives me the position relative to the window very handily, but I need to subtract the position of the image. I've found lots of code which returns me blankness.

JavaScript

function FindPosition(oElement) {
    if (typeof (oElement.offsetParent) != "undefined") {
        for (var posX = 0, posY = 0; oElement; oElement = oElement.offsetParent) {
            posX += oElement.offsetLeft;
            posY += oElement.offsetTop;
        }
        return [posX, posY];
    }
    else {
        return [oElement.x, oElement.y];
    }
}

JavaScript

function myMoveFunction()
{
   var pos = FindPosition(document.getElementbyID("imagebutton1"));
   document.getElementById("ImageCaption").innerHTML = "Coords: " + pos[0]+ ", " + pos[1] ;
}

Gives me only blank in my imagecaption

Posted 13-Oct-14 6:49am

Troublesome Tommy

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Sergey Alexandrovich Kryukov · Answer 1 · 2014-10-13T07:05:00

Solution 1

What would you expect? In your method FindPosition, you are not even trying to do anything related to the mouse.

You can get mouse coordinates from the event argument of the event itself. The most convenient way of doing it would be using jQuery: http://api.jquery.com/mousemove[^].

If you need to learn jQuery (highly recommended), please see:
http://en.wikipedia.org/wiki/JQuery[^],
http://jquery.com[^],
http://learn.jquery.com[^],
http://learn.jquery.com/using-jquery-core[^],
http://learn.jquery.com/about-jquery/how-jquery-works[^] (start from here).

To do it without any library, please use the event object and event properties clientX and clientY:
http://javascript.info/tutorial/mouse-events#mouse-coordinates-clientx-y-pagex-y[^].

—SA

Posted 13-Oct-14 7:05am

Sergey Alexandrovich Kryukov

Updated 13-Oct-14 7:06am

v2

Comments

Troublesome Tommy 13-Oct-14 19:00pm

I already have the mouse position from the event. I just need to find the position of the stupid control.

Sergey Alexandrovich Kryukov 13-Oct-14 19:35pm

Find? What do you mean by "finding"?
—SA

Troublesome Tommy 14-Oct-14 9:31am

I can see this is going to be real helpful.

Sergey Alexandrovich Kryukov 14-Oct-14 12:11pm

I'm sure you will solve it. The method I mentioned will give you the mouse pointer location on client coordinates.
Please use it and accept the answer formally (green "Accept" button).
In all cases, your follow-up questions will be welcome.
—SA

Troublesome Tommy 14-Oct-14 13:07pm

Well, the consensus on jquery is "Don't try to live without it."

So, to get this stupid little app working before I dive in to learn a whole new library, I now have

(No code in a "Comment?")


    function getOffset(el) {
        var _x = 0;
        var _y = 0;
        while (el && !isNaN(el.offsetLeft) && !isNaN(el.offsetTop)) {
            _x += el.offsetLeft - el.scrollLeft;
            _y += el.offsetTop - el.scrollTop;
            el = el.offsetParent;
        }
        return { top: _y, left: _x };
    }

    function myMoveFunction() {
        var x = getOffset(document.getElementById('TheDiv')).left;
        var y = 7;//getOffset(document.getElementByID('TheDiv')).top;
        document.getElementById("demo").innerHTML = event.x - x;
        document.getElementById("y2").innerHTML = event.y-y;
    }

But if I change y to the getoffset line instead of 7, the myMoveFunction doesn't do anything. See it at http://thinktulsa17.com/vendorhall/mousetest.html

Sergey Alexandrovich Kryukov 14-Oct-14 14:02pm

Pass event, not element! (Or pass both.)
Did't I explain: the coordinated is passed in event arguments? See the referenced article.
—SA