rescript/scripts/jsconfig.json

ReScript toolchain

{
    "compilerOptions": {
        "alwaysStrict": true
        , "noImplicitAny": true
        // , "strictNullChecks": true
        , "target": "es2018"
        // target need be set up
        // otherwise some method is missing
        , "module": "commonjs"
        // setup to understand commonjs module
    }   
}