判断移动端、PC端

var ua = navigator.userAgent;
	var ipad = ua.match(/(iPad).*OS\s([\d_]+)/),
    isIphone = !ipad && ua.match(/(iPhone\sOS)\s([\d_]+)/),
    isAndroid = ua.match(/(Android)\s+([\d.]+)/),
    isMobile = isIphone || isAndroid;
    if(isMobile) {
        location.href = 'GOTO m.xxx.com';
    }else{
        location.href = 'GOTO www.xxx.com';
    }

    //或者单独判断iphone或android 
    if(isIphone){
        //code 
    }else if(isAndroid){
        //code
    }else{
        //code
    }