自动识别电脑版和手机版来跳转css样式

<script>
    function loadCSS() {
        if((navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|wOSBrowser|BrowserNG|WebOS)/i))) {
            document.write('<link href="assets/css/index_mobile.css" rel="stylesheet" type="text/css" media="screen" />');
        }
        else {
            document.write('<link href="assets/css/index.css" rel="stylesheet" type="text/css" media="screen" />');
        }
    }
    loadCSS();
</script>