How to set javascript ecmascript version in sonarjs?

I am currently using sonarqube for codecovergae.Karma and jasmine as testing tool. Due to project complexity and dependency, i m using babel transpiler to convert ts to es5.

I am able to configure sonar-qube. However i am getting code smell like Replace "var" with "let" or "const". I check sonar configuration. I didnt find anything where i can set ecmascript version just like "sonar.java.source=1.6" My current configuration:

sonar.host.url=http://sonar.dev.***.com
sonar.projectKey=org.sonarqube:some-key
sonar.projectName=Project name
sonar.projectVersion=1.0
sonar.language=js
sonar.sources=temp/src
sonar.sourceEncoding=UTF-8
sonar.javascript.lcov.reportPath=coveragereports/coverage/lcov.info

Please help.