Add new initRecaptchaScript memoized function

- Add a memoized `initRecaptchaScript` function, which attaches the reCAPTCHA script to the document head. - It returns a Promise which resolves when the reCAPTCHA script has finished initialization.

Add new initRecaptchaScript memoized function
- Add a memoized `initRecaptchaScript` function, which attaches the reCAPTCHA script to the document head. - It returns a Promise which resolves when the reCAPTCHA script has finished initialization.
ead47d77 · Chad Woolley · Paul Slaughter · 578ab1bb · ead47d77 · ead47d77
Commit ead47d77 authored Jan 28, 2021 by Chad Woolley Committed by Paul Slaughter Jan 28, 2021
2 changed files
--- a/app/assets/javascripts/captcha/init_recaptcha_script.js
+++ b/app/assets/javascripts/captcha/init_recaptcha_script.js
+// NOTE: This module will be used in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/52044
+import { memoize } from 'lodash';
+
+export const RECAPTCHA_API_URL_PREFIX = 'https://www.google.com/recaptcha/api.js';
+/**
+ * The name which will be used for the reCAPTCHA script's onload callback
+ */
+export const RECAPTCHA_ONLOAD_CALLBACK_NAME = 'recaptchaOnloadCallback';
+
+/**
+ * Adds the Google reCAPTCHA script tag to the head of the document, and
+ * returns a promise of the grecaptcha object
+ * (https://developers.google.com/recaptcha/docs/display#js_api).
+ *
+ * It is memoized, so there will only be one instance of the script tag ever
+ * added to the document.
+ *
+ * See the reCAPTCHA documentation for more details:
+ *
+ * https://developers.google.com/recaptcha/docs/display#explicit_render
+ *
+ */
+export const initRecaptchaScript = memoize(() => {
+  /**
+   * Appends the the reCAPTCHA script tag to the head of document
+   */
+  const appendRecaptchaScript = () => {
+    const script = document.createElement('script');
+    script.src = `${RECAPTCHA_API_URL_PREFIX}?onload=${RECAPTCHA_ONLOAD_CALLBACK_NAME}&render=explicit`;
+    script.classList.add('js-recaptcha-script');
+    document.head.appendChild(script);
+  };
+
+  /**
+   * Returns a Promise which is fulfilled after the reCAPTCHA script is loaded
+   */
+  return new Promise((resolve) => {
+    window[RECAPTCHA_ONLOAD_CALLBACK_NAME] = resolve;
+    appendRecaptchaScript();
+  });
+});
+
+/**
+ * Clears the cached memoization of the default manager.
+ *
+ * This is needed for determinism in tests.
+ */
+export const clearMemoizeCache = () => {
+  initRecaptchaScript.cache.clear();
+};
--- a/spec/frontend/captcha/init_recaptcha_script_spec.js
+++ b/spec/frontend/captcha/init_recaptcha_script_spec.js
+import {
+  RECAPTCHA_API_URL_PREFIX,
+  RECAPTCHA_ONLOAD_CALLBACK_NAME,
+  clearMemoizeCache,
+  initRecaptchaScript,
+} from '~/captcha/init_recaptcha_script';
+
+describe('initRecaptchaScript', () => {
+  afterEach(() => {
+    // NOTE: The DOM is guaranteed to be clean at the start of a new test file, but it isn't cleaned
+    // between examples within a file, so we need to clean it after each one.  See more context here:
+    // - https://github.com/facebook/jest/issues/1224
+    // - https://stackoverflow.com/questions/42805128/does-jest-reset-the-jsdom-document-after-every-suite-or-test
+    //
+    // Also note as mentioned in https://github.com/facebook/jest/issues/1224#issuecomment-444586798
+    // that properties of `window` are NOT cleared between test files. So, we are also
+    // explicitly unsetting it.
+    document.head.innerHTML = '';
+    window[RECAPTCHA_ONLOAD_CALLBACK_NAME] = undefined;
+    clearMemoizeCache();
+  });
+
+  const triggerScriptOnload = (...args) => window[RECAPTCHA_ONLOAD_CALLBACK_NAME](...args);
+
+  describe('when called', () => {
+    let result;
+
+    beforeEach(() => {
+      result = initRecaptchaScript();
+    });
+
+    it('adds script to head', () => {
+      expect(document.head).toMatchInlineSnapshot(`
+        <head>
+          <script
+            class="js-recaptcha-script"
+            src="${RECAPTCHA_API_URL_PREFIX}?onload=${RECAPTCHA_ONLOAD_CALLBACK_NAME}&render=explicit"
+          />
+        </head>
+      `);
+    });
+
+    it('is memoized', () => {
+      expect(initRecaptchaScript()).toBe(result);
+      expect(document.head.querySelectorAll('script').length).toBe(1);
+    });
+
+    it('when onload is triggered, resolves promise', async () => {
+      const instance = {};
+
+      triggerScriptOnload(instance);
+
+      await expect(result).resolves.toBe(instance);
+    });
+  });
+});