increment.js

exports.increment = function(val) {
    return val + 1;
};

program.js

var inc = require('increment').increment;
var a = 1;
altert(inc(a)); // 2

start.html

<script type="text/javascript" src="inject.js"></script>
<script type="text/javascript">
  reqiure.setModuleRoot("http://example.com/js/modules");
  require.run("program");
</script>