switched/webpack/module/rules/i18n.ts

/**
 * Replace i18n texts
 */

const StringReplacePlugin = require('string-replace-webpack-plugin');

export default (lang, locale) => {
	function get(key: string) {
		let text = locale;

		// Check the key existance
		const error = key.split('.').some(k => {
			if (text.hasOwnProperty(k)) {
				text = text[k];
				return false;
			} else {
				return true;
			}
		});

		if (error) {
			console.warn(`key '${key}' not found in '${lang}'`);
			return key; // Fallback
		} else {
			return text;
		}
	}

	return {
		enforce: 'pre',
		test: /\.(tag|js|ts)$/,
		exclude: /node_modules/,
		loader: StringReplacePlugin.replace({
			replacements: [{
				pattern: /"%i18n:(.+?)%"/g, replacement: (_, key) =>
					'"' + get(key).replace(/"/g, '\\"') + '"'
			}, {
				pattern: /'%i18n:(.+?)%'/g, replacement: (_, key) =>
					'\'' + get(key).replace(/'/g, '\\\'') + '\''
			}, {
				pattern: /%i18n:(.+?)%/g, replacement: (_, key) =>
					get(key)
			}]
		})
	};
};