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feat(localize): support google translate

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Thijs Louisse 2020-06-06 14:32:00 +02:00 committed by Thomas Allmer
parent 8d9225c040
commit 271520d55c
3 changed files with 284 additions and 49 deletions
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43
packages/localize/docs/40-google-translate-integration.md Normal file
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@ -0,0 +1,43 @@
# Google Translate integration
```js script
export default {
title: 'Localize/Google Translate Integration',
};
```
When Google Translate is enabled, it takes control of the html[lang] attribute.
Below, we find a simplified example that illustrates this.
## The problem
A developer initializes a page like this (and instructs localize to fetch data for `en-US` locale)
```html
<html lang="en-US"></html>
```
If Google Translate is enabled and set to French, it will change html[lang]:
to `<html lang="fr">`
Now `localize` will fetch data for locale `fr`. There are two problems here:
- There might be no available data for locale `fr`
- Let's imagine data were loaded for `fr`. If Google Translate is turned off again,
the page content will consist of a combination of different locales.
## How to solve this
To trigger support for Google Translate, we need to configure two attributes
```html
<html lang="en-US" data-localize-lang="en-US"></html>
```
- html[data-localize-lang] will be read by `localize` and used for fetching data
- html[lang] will be configured for accessibility purposes (it will makes sure the
page is accessible if localize would be lazy loaded).
When Google Translate is set to French, we get: `<html lang="fr" data-localize-lang="en-US">`
The page is accessible and `localize` will fetch the right resources

86
packages/localize/src/LocalizeManager.js
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@ -11,10 +11,6 @@ export class LocalizeManager extends LionSingleton {
super(params);
this._fakeExtendsEventTarget();
if (!document.documentElement.lang) {
document.documentElement.lang = 'en-GB';
}
this._autoLoadOnLocaleChange = !!params.autoLoadOnLocaleChange;
this._fallbackLocale = params.fallbackLocale;
this.__storage = {};
@ -23,24 +19,80 @@ export class LocalizeManager extends LionSingleton {
this.__namespaceLoaderPromisesCache = {};
this.formatNumberOptions = { returnIfNaN: '' };
/**
* Via html[data-localize-lang], developers are allowed to set the initial locale, without
* having to worry about whether locale is initialized before 3rd parties like Google Translate.
* When this value differs from html[lang], we assume the 3rd party took
* control over the page language and we set this._langAttrSetByTranslationTool to html[lang]
*/
const initialLocale = document.documentElement.getAttribute('data-localize-lang');
this._supportExternalTranslationTools = Boolean(initialLocale);
if (this._supportExternalTranslationTools) {
this.locale = initialLocale || 'en-GB';
this._setupTranslationToolSupport();
}
if (!document.documentElement.lang) {
document.documentElement.lang = this.locale || 'en-GB';
}
this._setupHtmlLangAttributeObserver();
}
_setupTranslationToolSupport() {
/**
* This value allows for support for Google Translate (or other 3rd parties taking control
* of the html[lang] attribute).
*
* Have the following scenario in mind:
* 1. locale is initialized by developer via html[data-localize-lang="en-US"] and
* html[lang="en-US"]. When localize is loaded (note that this also can be after step 2 below),
* it will sync its initial state from html[data-localize-lang]
* 2. Google Translate kicks in for the French language. It will set html[lang="fr"].
* This new language is not one known by us, so we most likely don't have translations for
* this file. Therefore, we do NOT sync this value to LocalizeManager. The manager should
* still ask for known resources (in this case for locale 'en-US')
* 3. locale is changed (think of a language dropdown)
* It's a bit of a weird case, because we would not expect an end user to do this. If he/she
* does, make sure that we do not go against Google Translate, so we maintain accessibility
* (by not altering html[lang]). We detect this by reading _langAttrSetByTranslationTool:
* when its value is null, we consider Google translate 'not active'.
*
* When Google Translate is turned off by the user (html[lang=auto]),
* `localize.locale` will be synced to html[lang] again
*
* Keep in mind that all of the above also works with other tools than Google Translate,
* but this is the most widely used tool and therefore used as an example.
*/
this._langAttrSetByTranslationTool = document.documentElement.lang || null;
}
teardown() {
this._teardownHtmlLangAttributeObserver();
}
// eslint-disable-next-line class-methods-use-this
get locale() {
if (this._supportExternalTranslationTools) {
return this.__locale;
}
return document.documentElement.lang;
}
set locale(value) {
const oldLocale = document.documentElement.lang;
this._teardownHtmlLangAttributeObserver();
document.documentElement.lang = value;
this._setupHtmlLangAttributeObserver();
let oldLocale;
if (this._supportExternalTranslationTools) {
oldLocale = this.__locale;
this.__locale = value;
if (this._langAttrSetByTranslationTool === null) {
this._setHtmlLangAttribute(value);
}
} else {
oldLocale = document.documentElement.lang;
this._setHtmlLangAttribute(value);
}
if (!value.includes('-')) {
this.__handleLanguageOnly(value);
@ -49,6 +101,12 @@ export class LocalizeManager extends LionSingleton {
this._onLocaleChanged(value, oldLocale);
}
_setHtmlLangAttribute(locale) {
this._teardownHtmlLangAttributeObserver();
document.documentElement.lang = locale;
this._setupHtmlLangAttributeObserver();
}
// eslint-disable-next-line class-methods-use-this
__handleLanguageOnly(value) {
throw new Error(`
@ -119,7 +177,17 @@ export class LocalizeManager extends LionSingleton {
if (!this._htmlLangAttributeObserver) {
this._htmlLangAttributeObserver = new MutationObserver(mutations => {
mutations.forEach(mutation => {
if (this._supportExternalTranslationTools) {
if (document.documentElement.lang === 'auto') {
// Google Translate is switched off
this._langAttrSetByTranslationTool = null;
this._setHtmlLangAttribute(this.locale);
} else {
this._langAttrSetByTranslationTool = document.documentElement.lang;
}
} else {
this._onLocaleChanged(document.documentElement.lang, mutation.oldValue);
}
});
});
}

202
packages/localize/test/LocalizeManager.test.js
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@ -1,5 +1,6 @@
import { expect, oneEvent, aTimeout } from '@open-wc/testing';
import sinon from 'sinon';
// eslint-disable-next-line import/no-unresolved
import { fetchMock } from '@bundled-es-modules/fetch-mock';
import { setupFakeImport, resetFakeImport, fakeImport } from '../test-helpers.js';
@ -27,11 +28,6 @@ describe('LocalizeManager', () => {
resetFakeImport();
});
it('initializes locale from <html> by default', () => {
manager = new LocalizeManager();
expect(manager.locale).to.equal('en-GB');
});
it('syncs locale back to <html> if changed', () => {
manager = new LocalizeManager();
manager.locale = 'nl-NL';
@ -63,16 +59,6 @@ describe('LocalizeManager', () => {
expect(event.detail.oldLocale).to.equal('en-GB');
});
it('fires "localeChanged" event if locale was changed via <html lang> attribute', async () => {
manager = new LocalizeManager();
setTimeout(() => {
document.documentElement.lang = 'en-US';
});
const event = await oneEvent(manager, 'localeChanged');
expect(event.detail.newLocale).to.equal('en-US');
expect(event.detail.oldLocale).to.equal('en-GB');
});
it('does not fire "localeChanged" event if it was set to the same locale', () => {
manager = new LocalizeManager();
const eventSpy = sinon.spy();
@ -432,30 +418,6 @@ describe('LocalizeManager', () => {
'nl-NL': { 'my-component': { greeting: 'Hallo!' } },
});
});
it('loads namespaces automatically when locale is changed via <html lang> attribute', async () => {
setupFakeImport('./my-component/en-GB.js', { default: { greeting: 'Hello!' } });
setupFakeImport('./my-component/nl-NL.js', { default: { greeting: 'Hallo!' } });
manager = new LocalizeManager({ autoLoadOnLocaleChange: true });
await manager.loadNamespace({
'my-component': locale => fakeImport(`./my-component/${locale}.js`, 25),
});
expect(manager.__storage).to.deep.equal({
'en-GB': { 'my-component': { greeting: 'Hello!' } },
});
document.documentElement.lang = 'nl-NL';
await aTimeout(); // wait for mutation observer to be called
await manager.loadingComplete;
expect(manager.__storage).to.deep.equal({
'en-GB': { 'my-component': { greeting: 'Hello!' } },
'nl-NL': { 'my-component': { greeting: 'Hallo!' } },
});
});
});
describe('loading extra features', () => {
@ -594,3 +556,165 @@ describe('LocalizeManager', () => {
});
});
});
describe('When supporting external translation tools like Google Translate', () => {
let manager;
const originalLang = document.documentElement.lang;
async function simulateGoogleTranslateOn(lang) {
document.documentElement.lang = lang;
}
async function simulateGoogleTranslateOff() {
document.documentElement.lang = 'auto';
}
function getInstance(cfg) {
LocalizeManager.resetInstance();
return LocalizeManager.getInstance(cfg || {});
}
afterEach(() => {
document.documentElement.removeAttribute('lang');
document.documentElement.removeAttribute('data-localize-lang');
});
after(() => {
document.documentElement.lang = originalLang;
});
describe('On initialization', () => {
/** A default scenario */
it('synchronizes from html[data-localize-lang] attribute to LocalizeManager', async () => {
document.documentElement.setAttribute('data-localize-lang', 'nl-NL');
document.documentElement.lang = 'nl-NL';
manager = getInstance();
expect(manager.locale).to.equal('nl-NL');
});
/** A scenario where Google Translate kicked in before initialization */
it(`synchronizes from html[data-localize-lang] attribute to LocalizeManager when html[lang]
has a different value`, async () => {
document.documentElement.setAttribute('data-localize-lang', 'en-US');
document.documentElement.lang = 'fr';
manager = getInstance();
expect(manager.locale).to.equal('en-US');
});
it("doesn't synchronize from html[lang] attribute to LocalizeManager", async () => {
document.documentElement.setAttribute('data-localize-lang', 'en-US');
manager = getInstance();
document.documentElement.lang = 'nl-NL';
expect(manager.locale).to.not.equal('nl-NL');
});
it('triggers support for external translation tools via data-localize-lang', async () => {
document.documentElement.removeAttribute('data-localize-lang');
manager = getInstance();
expect(manager._supportExternalTranslationTools).to.be.false;
document.documentElement.setAttribute('data-localize-lang', 'nl-NL');
manager = getInstance();
expect(manager._supportExternalTranslationTools).to.be.true;
});
});
describe('After initialization', () => {
it(`synchronizes from LocalizeManager to html[lang] when
3rd party translation tool is NOT in control`, async () => {
document.documentElement.removeAttribute('lang');
manager = getInstance();
expect(document.documentElement.lang).to.equal('en-GB');
manager.locale = 'nl-NL';
expect(document.documentElement.lang).to.equal('nl-NL');
});
it(`doesn't synchronize from LocalizeManager to html[lang] when
3rd party translation tool is in control`, async () => {
document.documentElement.setAttribute('data-localize-lang', 'en-US');
manager = getInstance();
await simulateGoogleTranslateOn('fr');
manager.locale = 'nl-NL';
expect(document.documentElement.lang).to.equal('fr');
});
it(`doesn't synchronize from html[lang] attribute to LocalizeManager`, async () => {
document.documentElement.setAttribute('data-localize-lang', 'en-US');
manager = getInstance();
manager.locale = 'nl-NL';
// When a 3rd party like Google Translate alters lang attr of the page, we want to
// keep this for accessibility, but it should NOT be synchronized to our manager.
await simulateGoogleTranslateOn('fr');
expect(manager.locale).to.equal('nl-NL');
});
it(`restores html[lang] when 3rd party translation tool is turned off again`, async () => {
manager = getInstance();
manager.locale = 'nl-NL';
await simulateGoogleTranslateOn('fr');
expect(document.documentElement.lang).to.equal('fr');
await simulateGoogleTranslateOff();
expect(document.documentElement.lang).to.equal('nl-NL');
});
});
});
describe('[deprecated] When not supporting external translation tools like Google Translate', () => {
let manager;
beforeEach(() => {
// makes sure that between tests the localization is reset to default state
document.documentElement.lang = 'en-GB';
});
afterEach(() => {
manager.teardown();
});
afterEach(() => {
fetchMock.restore();
resetFakeImport();
});
it('initializes locale from <html> by default', () => {
manager = new LocalizeManager({ supportExternalTranslationTools: false });
expect(manager.locale).to.equal('en-GB');
});
it('fires "localeChanged" event if locale was changed via <html lang> attribute', async () => {
manager = new LocalizeManager({ supportExternalTranslationTools: false });
setTimeout(() => {
document.documentElement.lang = 'en-US';
});
const event = await oneEvent(manager, 'localeChanged');
expect(event.detail.newLocale).to.equal('en-US');
expect(event.detail.oldLocale).to.equal('en-GB');
});
it('loads namespaces automatically when locale is changed via <html lang> attribute', async () => {
setupFakeImport('./my-component/en-GB.js', { default: { greeting: 'Hello!' } });
setupFakeImport('./my-component/nl-NL.js', { default: { greeting: 'Hallo!' } });
manager = new LocalizeManager({
supportExternalTranslationTools: false,
autoLoadOnLocaleChange: true,
});
await manager.loadNamespace({
'my-component': locale => fakeImport(`./my-component/${locale}.js`, 25),
});
expect(manager.__storage).to.deep.equal({
'en-GB': { 'my-component': { greeting: 'Hello!' } },
});
document.documentElement.lang = 'nl-NL';
await aTimeout(); // wait for mutation observer to be called
await manager.loadingComplete;
expect(manager.__storage).to.deep.equal({
'en-GB': { 'my-component': { greeting: 'Hello!' } },
'nl-NL': { 'my-component': { greeting: 'Hallo!' } },
});
});
});