Automatically and proportionally change iframe height for mobile and deskto

tekagami

Introduction
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.

Javascript Function
includes: the id of the iframe, the original width and original height

See code below.

the iframe

<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;
LastMitch commented: Nice! +11
Mark_43 commented: This is exactly what I needed. Thank you for your wonderful work +0
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About the Author

Web Designer, Attorney, Economist

function resizeiframecent(ifid, oldx, oldy) {
     
    var actualwidth = document.getElementById(ifid).offsetWidth;
     
    var proporcion = actualwidth / oldx;
    newheight=proporcion * oldy;
    var newheight2 = Math.ceil(newheight);
     
    document.getElementById(ifid).height = newheight2;
     
}
Member Avatar
LastMitch

Lets say you have a website with a mobile version and a desktop version.

Is this a tutorial?

If so, let a Moderator know so he will change this thread into a tutorial/code snippet thread

tekagami 23 Newbie Poster

Yes it is

Member Avatar
LastMitch

It's a nice code snippet.

I didn't know you can change the size on a iFrame by using javascript like that.

Thanks for sharing.

tekagami 23 Newbie Poster

Well in theory any element of html could be resized with it. The key is line 3 of the javascript where the actual size of the element is measured. Everything depends on having the offsetWidth give you a width.

HenryGR 0 Newbie Poster

Hey Rodrigo,
Nice snippet, Gracias!
Have you tested it cross browser?

tekagami 23 Newbie Poster

Yeah, chrome (win and ios), IE9 and 10 and safari (win iphone and ipad)

Hicaro_1 0 Newbie Poster

Excelente Rodrigo

onload="resizeiframecent(this,'1920','496')"

function resizeiframecent(ifid, oldx, oldy) {
    var actualwidth = ifid.offsetWidth;
    var proporcion = actualwidth / oldx;
    newheight=proporcion * oldy;
    var newheight2 = Math.ceil(newheight);
    ifid.height = newheight2;
}
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