Cheking urls considering protocol-relative url

[18choi18]

When using the Router in a specific part of the web page, in other parts they may not know that they should add a native boolean attribute to a link tag for bypassing preact-router's link handling. Currently, in this case, if an anchor tag have protocol-relative url(ex, //www.11st.co.kr) for the value of href, the link can't avoid handling of preact-router because it starts with '/'.

Therefore, unintended handling occurs in the a tag that takes the protocol-relative url as the value of href. So I suggest modifying the regex. From: If the value of href starts with '/'? To: If the value of href starts with '/' but the next character is not '/'?