I got this same warning when using an export statement. I'm using VS Code and used a similar approach to Wenlong Jiang's solution.
User Settings
JSHint config
"jshint.config": {}
(Edit)
Use double quotes when specifying "esversion"
Or copy this snippet into User Settings:
"jshint.options": {
"esversion": 6,
}
Creating a .jshintrc
file isn't necessary if you want to configure the global jshint settings for your editor