Lets say you have a website with a mobile version and a desktop version. Pictures can be resized proportinally using css on either version. But not all html tags resize proportionally, for instance: iframes.
includes: the id of the iframe, the original width and original height
See code below.
<iframe id="iemovie" onload="resizeiframecent('iemovie','800','450')" src="http://www.youtube.com/embed/J-HieaOI00s?html5=1" width="100%" > </iframe>
- notice the height is absent but the width is 100%. it will adjust to the parent element's width; usually a div with its preset width, say 800px for desktop, and 90% for mobile.
- notice the onload attribute
- when iframe loads the function takes the original proportions oldx and oldy and compares them to the actualwidth
- the math.ceil funtion rounds up the newheight and creates a new variable called newheight2
then, the iframe gets a newly defined height atribute based proportionally based on the original height
- do not set the iframe proportions via css or else you will have to change the code from document.getElementById(ifid).height=newheight2; to document.getElementById(ifid).style.height=newheight2;