How to check if a custom protocol supported
<p>We are using software that registers its own protocol. We can run application from browser then by link like:</p>

<pre><code>customprotocol://do_this.
</code></pre>

<p>but is there a way to check is such custom protocol supported by user`s system? If not we would like to ask user to install software first.</p>

<p>E.g:</p>

<pre><code>if (canHandle ('customprotocol')) {
     // run software
}
else {
    // ask to install
}
</code></pre>

<p><strong>Edit</strong>
I know about protocolLong property but it works only in IE.</p>
