added regexp file

Author: Code-Hex

src/regexp.ts

@@ -0,0 +1,3 @@
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#advanced_searching_with_flags
+export const isConvertableRegexp = (maybeRegexp: string): boolean =>
+  /^\/.*\/[dgimsuy]*$/.test(maybeRegexp);

tests/regexp.spec.ts

@@ -0,0 +1,36 @@
+import { isConvertableRegexp } from "../src/regexp";
+
+describe("isConvertableRegexp", () => {
+  describe("match", () => {
+    test.each([
+      "//",
+      "/hello/",
+      "/hello/d",
+      "/hello/g",
+      "/hello/i",
+      "/hello/m",
+      "/hello/s",
+      "/hello/u",
+      "/hello/y",
+      "/hello/dgimsuy",
+      `/\\w+\\s/g`,
+      `/^[a-z]+:[\\\/]$/i`,
+      `/^(?:\d{3}|\(\d{3}\))([-\/\.])\d{3}\\1\d{4}$/`,
+    ])("%s", (maybeRegexp) => {
+      expect(isConvertableRegexp(maybeRegexp)).toBeTruthy();
+    });
+  });
+  describe("does not match", () => {
+    test.each([
+      "hello",
+      "/world",
+      "world/",
+      "https://example.com/",
+      "  /hello/",
+      "/hello/d  ",
+      "/hello/dgimsuy  ",
+    ])("%s", (maybeRegexp) => {
+      expect(isConvertableRegexp(maybeRegexp)).toBeFalsy();
+    });
+  });
+});