The j:if tag is used to conditionally evaluate its body based on some expression. Unlike other programming languages, there aren't any else-if or else options. It accepts the following attribute:

• test: This is used to specify the Jelly expression (condition) to evaluate. If the expression evaluates to true, the body of the tag is evaluated.

For example:

<g:evaluatevar="jvar_gr" object="true"> 
var gr = new GlideRecord("x_8940_travel_book_booking_request"); 
gr.addQuery("active", true); 
gr.query(); 
gr; 
</g:evaluate> 
<j:if test="${!jvar_gr.hasNext()}"> 
We did not find any active incidents. 
</j:if> 
<j:if test="${jvar_gr.next()}"> 
We found ${jvar_gr.getRowCount()} active incidents. 
</j:if>