According to w3schools.com/tags/att_iframe_height.asp
In HTML 4.01, the height could be defined in pixels or in % of the containing element. In HTML5, the value must be in pixels.
if i want to create full screen iframe i can set the width and height to 100% , in HTML5 its no longer works,
What is the alternative, or do i need some kind of JS?
Jason Knight
The less code you use, the less there is to break
TECHNICALLY that's not HTML's job... width, height, borders, etc, etc... NEVER was supposed to exist despite all the CRAP that was added during the browser wars -- from Netscape and M$ trying to out-flashy each-other -- and wormed its way into the train wreck that was HTML 3.2 and/or 4 tranny.
Of course with most developers still having their craniums wedged up 1997's rectum in terms of the intent of HTML, what HTML 4 Strict was trying to drag us towards, and still pretty much vomiting up HTML 3.2 and slapping either 4 tranny atop or 5 lip-service around it... then they get to congratulate themselves over how "modern" they are as every beginner just blindly copies the outdated, outmoded, inaccessible practices.
Good rule of thumb, if you're saying what you want things to look like in your HTML, be it your tags, your classes, your id's, or inlined style="" and STYLE tags, you're doing it all wrong!
You want to control the height and width of something, that's CSS job. PREFERABLY external CSS.
Of course that the ignorant nube predator SCAM that is W3Fools even bothers listing that as a value without warnings says a lot about their alleged relevance and usefulness. You might want to try MDN instead.