js实现背景图自适应窗口大小

话不多说,请看代码 [removed] [removed] = [removed] = function() { var w,bgImg; if(!!(window.attachEvent && !window.opera)) { w = document.documentElement.clientWidth; } else { w = window.innerWidth; }if(w>1650){ document.getElementById ('msg').value ='窗口大小: