refactor: 改用 TypeScript。close #1.

lib/utils/files.ts

@@ -0,0 +1,23 @@
+import fs from 'fs'
+import path from 'path'
+
+const pipe =
+  (...fns) =>
+  (x) =>
+    fns.reduce((v, f) => f(v), x)
+
+const flattenArray = (input) =>
+  input.reduce((acc, item) => [...acc, ...(Array.isArray(item) ? item : [item])], [])
+
+const map = (fn) => (input) => input.map(fn)
+
+const walkDir = (fullPath: string) => {
+  return fs.statSync(fullPath).isFile() ? fullPath : getAllFilesRecursively(fullPath)
+}
+
+const pathJoinPrefix = (prefix: string) => (extraPath: string) => path.join(prefix, extraPath)
+
+const getAllFilesRecursively = (folder: string): string[] =>
+  pipe(fs.readdirSync, map(pipe(pathJoinPrefix(folder), walkDir)), flattenArray)(folder)
+
+export default getAllFilesRecursively