如何在Internet Explorer 7中获得缩放级别？ （JavaScript的）

Question

In Internet Explorer 7 some properties (mouse coordinates) are treated as physical while others are logical (offset). This essentially required Web developers to be aware of or calculate the zoom state. In IE8 release all properties are logical.

Answer 1

You can get it using:

var b = document.body.getBoundingClientRect();    
alert((b.right - b.left)/document.body.clientWidth);

Thanks a lot @niclasnorgren !

Answer 2

Also, if you need to do check in IE 8, you can use window.screen.deviceXDPI and window.screen.deviceYDPI. The default is 96 dpi, and if you're zoomed, the number will be larger (aka 144 when zoomed 150%)

Answer 3

There is a small syntax error (body instead of document.body) on the accepted answer. This seems to do the trick also.

var rect = document.body.getBoundingClientRect(); 
var zoomLevel = Math.round((rect.right-rect.left)/document.body.clientWidth * 100); 

Answer 4

i have posted solution for this on another post you can get this here. which will work in IE7 also.

Auto-detect a screen resolution and change browser zoom with Javascript?

This will help to detect browser zoom tested on all browser
<script>
window.utility = function(utility){
utility.screen = {
    rtime : new Date(1, 1, 2000, 12,00,00),
    timeout : false,
    delta : 200
};
utility.getBrowser = function(){
    var $b = $.browser;
    $.extend(utility.screen,$.browser);
    utility.screen.isZoomed = false;
    var screen  = utility.screen;
    screen.zoomf  = screen.zoom = 1;
    screen.width = window.screen.width;
    screen.height = window.screen.height;
    if($b.mozilla){ //FOR MOZILLA
        screen.isZoomed  = window.matchMedia('(max--moz-device-pixel-ratio:0.99), (min--moz-device-pixel-ratio:1.01)').matches;
    } else {
        if($b.chrome){ //FOR CHROME
            screen.zoom = (window.outerWidth - 8) / window.innerWidth;
            screen.isZoomed = (screen.zoom < .98 || screen.zoom > 1.02)
        } else if($b.msie){//FOR IE7,IE8,IE9
            var _screen = document.frames.screen;
            screen.zoom = ((((_screen.deviceXDPI / _screen.systemXDPI) * 100 + 0.9).toFixed())/100);
            screen.isZoomed = (screen.zoom < .98 || screen.zoom > 1.02);
            if(screen.isZoomed) screen.zoomf = screen.zoom;
            screen.width = window.screen.width*screen.zoomf;
            screen.height = window.screen.height*screen.zoomf;
        }
    }
    return utility.screen;
};
  window.onresize = function(e){
       utility.screen.rtime = new Date();
        if (utility.screen.timeout === false) {
              utility.screen.timeout = true;
              setTimeout(window.resizeend, utility.screen.delta);
        }
  };
window.resizeend = function() {
    if (new Date() - utility.screen.rtime < utility.screen.delta) {
        setTimeout(window.resizeend, utility.screen.delta);
    } else {
        utility.screen.timeout = false;
        utility.screen = utility.getBrowser();
        if(window.onresizeend) window.onresizeend (utility.screen);
        if(utility.onResize) utility.onResize(utility.screen);
    }               
};
window.onresizeend = function(screen){
    if(screen.isZoomed)
        $('body').text('zoom is not 100%');
    else{
        $('body').text('zoom is 100% & browser resolution is'+[screen.width+'X'+screen.height]);
    }
};
$(document).ready(function(){
    window.onresize();
});
return utility;
}({});
</script>

Demo