Calling a function in an external JavaScript from a sandboxed HTML -

i'm helping develop chrome application, google blockly , js interpreter sandboxed. here's root directory looks like:

below directory of blockly folder:

i included blockly/index.html in manifest.json sandbox it:

"sandbox": {    "pages": ["blockly/index.html"] } 

i tried call function dosomething() in js/core/editorjavascript.js in blockly/index.html this:

<script src="../js/core/editorjavascript.js"></script> //other code function example() {   espruino.core.editorjavascript.dosomething(parameter); } 

however doesn't seem work - keep getting error chrome, suggests editorjavascript.js can't seen index.html when it's included (i'm suspecting it's double dots - allowed in sandbox?):

uncaught referenceerror: espruino not defined

so question is, possible call function in external js sandboxed html? if is, doing wrong? if it's not, there alternative problem? advice appreciated , thank in advance.