How to use javascript inside xhtml files

I have a js file(abc.js) and having a function increment().Which stores count of places as var noOfPlaces.

In the xhtml file.Have a component which is having onclick function.

I want to have if else condition inside onclick based on noOfPlaces.

abc.js

function increment(){
var noOfPlaces=(some methods);

cde.xhtml

 <a4j:commandLink id="Import" type="submit"
 rendered="#{()}"
onclick="focusOn('Import');if else condition

How can we use jaavascrpt variable value in xhtml page and write if else condition in onlick> I know how to use javamethods in xhtml (classname.methodname).How can we do for js file Thanks in advance