移动端屏幕尺寸自适应

var metaEl = document.querySelector('meta[name="viewport"]');
var scale;
scale = document.documentElement.clientWidth / 320;
metaEl.setAttribute("content", "width=320,initial-scale=" + scale + ",maximum-scale=" + scale + ",user-scalable=no");
var ispc = function() {
var userAgentInfo = navigator.userAgent;
var Agents = ["Android", "iPhone", "SymbianOS", "Windows Phone", "iPad", "iPod"];
var flag = true;
for (var v = 0; v < Agents.length; v++) {
if (userAgentInfo.indexOf(Agents[v]) > 0) {
flag = false;
break
}
}
return flag
};