Scrolling HTML Basics, Part II: Positioning A Scroll Box - www.docjavascript.com | WebReference

Scrolling HTML Basics, Part II: Positioning A Scroll Box - www.docjavascript.com


Positioning A Scroll Box

There are many ways to position a scroll box. You can position it in absolute coordinates, but the desired location may change because of an ad put at the top of the page, for example. In this column we use the GIF method. We place a dummy GIF wherever we want in our page:

<IMG SRC="blank.gif"
        NAME="holdspace" ID="holdspace"
        WIDTH="350" HEIGHT="90"
        STYLE="visibility:hidden; position:relative;">

We then compute the coordinates of this GIF in our scrolling box code:

var holdingImage = document.images["holdspace"];
var canvasLeft = holdingImage.offsetLeft;
var canvasTop = holdingImage.offsetTop;
var canvasWidth = holdingImage.width;
var canvasHeight = holdingImage.height;

and we use these coordinates to set the scroll box, as explained in previous pages.

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Produced by Yehuda Shiran and Tomer Shiran

Created: December 7, 1998
Revised: December 7, 1998

URL: http://www.webreference.com/js/column31/position.html