html - Restrict Multiple selections in dropdown -

i want user select 2 values in html dropdown. please can suggestion how can this. code using mentioned below.

<select style="width: 300px;height:200px;" name="graphlistbox" multiple="multiple" id="graphlistbox"> <c:foreach items="${graphlist}" var="graphtype">     <option value="${graphtype}"><c:out value="${graphtype}" /></option> </c:foreach> </select> 

plain html not support this. can use javascript catch situation.

jquery hard work you: https://stackoverflow.com/a/4135296/2536029