$root not working in web env with es6 import nor require #30

// download st.js to my local disk
var ST = require('./st.js'); 
// import ST  from './st.js';
var data = {
   a: 100,
   lists:[1,2,3]
}
var template = {
            "dt": "section_list",
            "sections": {
              "{{#each lists}}": [{
                  "{{#if $root.a > 0}}":{
                      "text": "sfsfs"
                }
              }]
            }
          }


//
ST.select(data)
	.transformWith(template)
	.root()

// output
{
	"dt": "section_list",
	"sections": [
		[{
			"{{#if $root.a > 0}}": {
				"text": "sfsfs"
			}
		}],
		[{
			"{{#if $root.a > 0}}": {
				"text": "sfsfs"
			}
		}],
		[{
			"{{#if $root.a > 0}}": {
				"text": "sfsfs"
			}
		}]
	]
}