一段字符中匹配出网址，可以将css里复制的url(blabla)匹配网址，方便下载

<!DOCTYPE html>
<html>

    <head>
        <meta charset="UTF-8">
        <title>match</title>
        <script type="text/javascript">
            window.onload = function() {
                var str = "url(http://img2.cache.netease.com/f2e/wap/touch_index_2016/trunk/images/download_2017.png) no-repeat";

                var regex = "\\((.+?)\\)"; //匹配括号内内容
                var arr = str.match(regex);
//                var reg = /http:\/\/\w*(\.\w*)+/ig;//匹配网址
                console.log(arr[1]);
// var reg = /^([a-zA-Z0-9_-])+@([a-zA-Z0-9_-])+((\.[a-zA-Z0-9_-]{2,3}){1,2})$/; 匹配邮箱

                btn.onclick = function() {
                    var text = document.getElementById('text');
                    var result = document.getElementById('result');
                    var str1 = text.value;
                    var arr1 = str1.match(regex);
                    console.log(arr1[1]);
                    result.innerHTML = arr1[1];
                    result.href = arr1[1];
                }

            }
        </script>
        <input type="text" name="text" id="text" placeholder="粘贴至此" value="" />
        <button id="btn">链接</button>
        <a href="#" id="result"></a>
    </head>

    <body>
    </body>

</html>

 https://regexper.com/#%5C%5C((.%2B%3F)%5C%5C)