JS 获取浏览器显示比例，缩放比例

JS不能调整浏览器的显示比例，仅能查看

//调整浏览器显示比例【仅能查看】
function ChangeRatio()
{
    var ratio=0;
    var screen=window.screen;
    var ua=navigator.userAgent.toLowerCase();

    if(window.devicePixelRatio !== undefined)
    {
        ratio=window.devicePixelRatio;    
    }
    else if(~ua.indexOf('msie'))
    {
        if(screen.deviceXDPI && screen.logicalXDPI)
        {
            ratio=screen.deviceXDPI/screen.logicalXDPI;        
        }
    
    }
    else if(window.outerWidth !== undefined && window.innerWidth !== undefined)
    {
        ratio=window.outerWidth/window.innerWidth;
    }

    if(ratio)
    {
        ratio=Math.round(ratio*100);    
    }
    return ratio;
}