I writed and checked my js code in GWT. For checking I added my js code in (projectName).html file and it is worked.
But when I try added external js file I get an error:
WARN] 404 - GET <path to js file>someJsFile.js (127.0.0.1) 1452 bytes
Request headers
I added this line to (projectName).gwt.xml file:
<script src="src/main/resources/<projectName>/someJsFile.js"></script>