Force Page Zoom at 100% with Js

Force page zoom at 100% with JS

You can set zoom property on page load

document.body.style.zoom = 1.0

But, zoom is not a standard property for all browsers, I recommend using transform instead.

var scale = 'scale(1)';
document.body.style.webkitTransform =  scale;    // Chrome, Opera, Safari
 document.body.style.msTransform =   scale;       // IE 9
 document.body.style.transform = scale;     // General

http://jsfiddle.net/5RzJ8/

Changing the browser zoom level

I would say not possible in most browsers, at least not without some additional plugins. And in any case I would try to avoid relying on the browser's zoom as the implementations vary (some browsers only zoom the fonts, others zoom the images, too etc). Unless you don't care much about user experience.

If you need a more reliable zoom, then consider zooming the page fonts and images with JavaScript and CSS, or possibly on the server side. The image and layout scaling issues could be addressed this way. Of course, this requires a bit more work.

How to detect page zoom level in all modern browsers?

Now it's an even bigger mess than it was when this question was first asked. From reading all the responses and blog posts I could find, here's a summary. I also set up this page to test all these methods of measuring the zoom level. [↑ broken link. Archived copy → here].

Edit (2011-12-12): I've added a project that can be cloned: https://github.com/tombigel/detect-zoom

• IE8: screen.deviceXDPI / screen.logicalXDPI (or, for the zoom level relative to default zoom, screen.systemXDPI / screen.logicalXDPI)
• IE7: var body = document.body,r = body.getBoundingClientRect(); return (r.left-r.right)/body.offsetWidth; (thanks to this example or this answer)
• FF3.5 ONLY: screen.width / media query screen width (see below) (takes advantage of the fact that screen.width uses device pixels but MQ width uses CSS pixels--thanks to Quirksmode widths)
• FF3.6: no known method
• FF4+: media queries binary search (see below)
• WebKit: https://www.chromestatus.com/feature/5737866978131968 (thanks to Teo in the comments)
• WebKit: measure the preferred size of a div with -webkit-text-size-adjust:none.
• WebKit: (broken since r72591) document.width / jQuery(document).width() (thanks to Dirk van Oosterbosch above). To get ratio in terms of device pixels (instead of relative to default zoom), multiply by window.devicePixelRatio.
• Old WebKit? (unverified): parseInt(getComputedStyle(document.documentElement,null).width) / document.documentElement.clientWidth (from this answer)
• Opera: document.documentElement.offsetWidth / width of a position:fixed; width:100% div. from here (Quirksmode's widths table says it's a bug; innerWidth should be CSS px). We use the position:fixed element to get the width of the viewport including the space where the scrollbars are; document.documentElement.clientWidth excludes this width. This is broken since sometime in 2011; I know no way to get the zoom level in Opera anymore.
• Other: Flash solution from Sebastian
• Unreliable: listen to mouse events and measure change in screenX / change in clientX

Here's a binary search for Firefox 4, since I don't know of any variable where it is exposed:

<style id=binarysearch></style>
<div id=dummyElement>Dummy element to test media queries.</div>
<script>
var mediaQueryMatches = function(property, r) {
  var style = document.getElementById('binarysearch');
  var dummyElement = document.getElementById('dummyElement');
  style.sheet.insertRule('@media (' + property + ':' + r +
                         ') {#dummyElement ' +
                         '{text-decoration: underline} }', 0);
  var matched = getComputedStyle(dummyElement, null).textDecoration
      == 'underline';
  style.sheet.deleteRule(0);
  return matched;
};
var mediaQueryBinarySearch = function(
    property, unit, a, b, maxIter, epsilon) {
  var mid = (a + b)/2;
  if (maxIter == 0 || b - a < epsilon) return mid;
  if (mediaQueryMatches(property, mid + unit)) {
    return mediaQueryBinarySearch(
        property, unit, mid, b, maxIter-1, epsilon);
  } else {
    return mediaQueryBinarySearch(
        property, unit, a, mid, maxIter-1, epsilon);
  }
};
var mozDevicePixelRatio = mediaQueryBinarySearch(
    'min--moz-device-pixel-ratio', '', a, b, maxIter, epsilon);
var ff35DevicePixelRatio = screen.width / mediaQueryBinarySearch(
    'min-device-width', 'px', 0, 6000, 25, .0001);
</script>

How to Increase browser zoom level on page load?

Personally I think this is a bad idea; either design your site so it scales easily (not hard with proper CSS/HTML techniques). Typically you should not make UX decisions for people.

But it is possible.

Demo: http://jsfiddle.net/q6kebgbh/4/

.zoom {
    zoom: 2;
    -moz-transform: scale(2);
    -moz-transform-origin: 0 0;
}

Note that previous versions of this answer used transform to support more browsers. However, this shortened code appears to work for current versions of Chrome, FF, Safari and IE (as well as previous versions of IE, which have supported zoom for a long time).

force webpage to open in 100% zoom (in IE8)

http://msdn.microsoft.com/en-us/library/ms531189(v=vs.85).aspx

"Windows Internet Explorer 8. The
-ms-zoom attribute is an extension to CSS, and can be used as a synonym for
zoom in IE8 mode."

Having said that, I haven't tried it to know how it behaves, and you shouldn't force a particular size on a user (as @Brad stated).

All modern browsers do a nice job of scaling things smoothly both up and down, so I wouldn't worry about it too much.

EDIT: your site looks fine in Chrome and IE8 on my machine (in which it opens at 100% on my machine anyway, so check your browser settings. This whole discussion may be moot).

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