Retrieve the position (X,Y) of an HTML element relative to the browser window

Question

I want to know how to get the X and Y position of HTML elements such as img and div in JavaScript relative to the browser window.

Answer 1

You can add two properties to Element.prototype to get the top/left of any element.

Object.defineProperty( Element.prototype, 'documentOffsetTop', {
    get: function () { 
        return this.offsetTop + ( this.offsetParent ? this.offsetParent.documentOffsetTop : 0 );
    }
} );

Object.defineProperty( Element.prototype, 'documentOffsetLeft', {
    get: function () { 
        return this.offsetLeft + ( this.offsetParent ? this.offsetParent.documentOffsetLeft : 0 );
    }
} );

This is called like this:

var x = document.getElementById( 'myDiv' ).documentOffsetLeft;

Here's a demo comparing the results to jQuery's offset().top and .left: http://jsfiddle.net/ThinkingStiff/3G7EZ/