.explain.md

First, generate .flow file.

$ yarn run flow gen-flow-files --out-dir . greeting.js

Genereted file is almost the same as greeting.js.flow.

Next, run flow and get an error like below.

Error: greeting.js.flow:6
  6: declare export var greeting: "\227\129\147\227\130\147\227\129\171\227\129\161\227\129\175";
                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Octal literals are not allowed in strict mode.

.flowconfig

[ignore]

[include]

[libs]

[lints]

[options]

[strict]

greeting.js

// @flow
export const greeting: "こんにちは" = "こんにちは"

greeting.js.flow

// @flow

// This .flow file is generated by commnd below.
// $ yarn run flow gen-flow-files --out-dir . greeting.js

declare export var greeting: "\227\129\147\227\130\147\227\129\171\227\129\161\227\129\175";

package.json

{
  "dependencies": {
    "flow-bin": "^0.63.1"
  }
}

yarn.lock

# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
# yarn lockfile v1


flow-bin@^0.63.1:
  version "0.63.1"
  resolved "https://registry.yarnpkg.com/flow-bin/-/flow-bin-0.63.1.tgz#ab00067c197169a5fb5b4996c8f6927b06694828"