understanding viewport width for responsive design

Question

after reading a lot about browser viewport width issues, I concluded to make a trial to see that if I understood the concept.

I used javascript below: This script prints "Your viewport width is WidthxHeight"

Element 1: At a 1920 x 1080 resolution, HP x2301 screen without any scroll bar: JS printed: Your viewport width is 1920x955

Element 2: At a 1920 x 1080 resolution, HP x2301 screen with scroll bar (I increased the height of page with lots of lorem Ipsum string paragraphs): JS printed: Your viewport width is 1920x955

Element3: At Chrome, I inspected element1 view and element2 view. For element 2, with scroll bar, Chrome wrote width as 1903 pixel, not 1920.

My questions are:

Why element1 and element2 gave the same width? For element2, I was expecting new width = (1920 - scroll bar width). For example Chrome wrote 1903 pixel in its inspection tool.
I declared <meta name="viewport" content="initial-scale=1, width=device-width"> in my header as a meta tag. And in my CSS3, I declared @media screen and (max-width: 1000px) { change something for responsiveness } Since my aim is to be responsive in browser's viewport, does these 2 combination OK? At this point I should say that my viewport definition and aim is pure display width without vertical scroll bar. Because of my understanding, max-width:1000px means to me: be responsive in layout just after pure display width is <=1000px

javascript source link is: http://andylangton.co.uk/blog/development/get-viewport-size-width-and-height-javascript

    <script type="text/javascript">
    <!--
     
     var viewportwidth;
     var viewportheight;
      
     // the more standards compliant browsers (mozilla/netscape/opera/IE7) use window.innerWidth and window.innerHeight
      
     if (typeof window.innerWidth != 'undefined')
     {
          viewportwidth = window.innerWidth,
          viewportheight = window.innerHeight
     }
      
    // IE6 in standards compliant mode (i.e. with a valid doctype as the first line in the document)
     
     else if (typeof document.documentElement != 'undefined'
         && typeof document.documentElement.clientWidth !=
         'undefined' && document.documentElement.clientWidth != 0)
     {
           viewportwidth = document.documentElement.clientWidth,
           viewportheight = document.documentElement.clientHeight
     }
      
     // older versions of IE
      
     else
     {
           viewportwidth = document.getElementsByTagName('body')[0].clientWidth,
           viewportheight = document.getElementsByTagName('body')[0].clientHeight
     }
    document.write('<p>Your viewport width is '+viewportwidth+'x'+viewportheight+'</p>');
    //-->
    </script>

thank you in advance, regards

score 0 · Accepted Answer · edited May 23 '17 at 12:21

I got the point.

I changed the JS and got the true viewport width.

JS owner is Vilmantas Baranauskas from SO family.

related SO link: Get the height and width of the browser viewport without scrollbars using jquery?

related script:

    <script type="text/javascript">     
        var viewportHeight;
        var viewportWidth;
        if (document.compatMode === 'BackCompat') {
            viewportHeight = document.body.clientHeight;
            viewportWidth = document.body.clientWidth;
        } else {
            viewportHeight = document.documentElement.clientHeight;
            viewportWidth = document.documentElement.clientWidth;
        }
        document.write('<p>Your viewport width without scrollbars is '+viewportHeight+'x'+viewportWidth+'</p>');
    </script>

1903 pixel width is true since scroll-bar std width is 17px as I know.

I also recommend to any one to use overflow-y:scroll; code in CSS Body or HTML tag in order to make browser display the scrollbar always even if for a blank draft web page.

understanding viewport width for responsive design

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