<script language="ecmascript" type="text/ecmascript">
 
 
    var clientContext = null;
    var web = null;
 
    function getWebProperties() {
 
        clientContext = new SP.ClientContext.get_current();
        web = clientContext.get_web();
        clientContext.load(web, 'Title', 'Description');
        clientContext.executeQueryAsync(Function.createDelegate(this, this.onQuerySucceeded), Function.createDelegate(this, this.onQueryFailed));
    }
 
    function onQuerySucceeded() {
 
        var message = "Web retrieved:";
        message += "\n Title: " + web.get_title();
        message += "\n Description: " + web.get_description();
        alert(message);
    }
 
 
    function onQueryFailed(sender, args) {
        alert('Request failed. ' + args.get_message() + '\n' + args.get_stackTrace());
    }
</script>


<input id="btnGetWebProperties" onclick="getWebProperties()" type="button" value="Get the web properties"/>