Exclude invalid translations from json (#3434)

tasks/compile-translations-po-to-json.js

@@ -11,6 +11,56 @@ function isDirectory(path) {
     }
 }
 
+/*
+
+It iterates all user supplied translations and removes placeholders found in the original string.
+If there are any additional placeholders left, the translation is considered invalid. It is whitespace sensitive.
+
+For example: `{"Update {{sequence}}": "Mettre à jour {{séquence}}"}`
+
+The original placeholder is `{{sequence}}`. It would be removed from the translation, but it doesn't contain it.
+An additional placeholder that was not in the original string is found - `{{séquence}}` and because of this
+the translation is considered invalid and will not be outputted to JSON.
+
+*/
+
+function removeInvalidTranslations(grunt, jsonFilePath, filename) {
+    var translations = JSON.parse(fs.readFileSync(jsonFilePath, 'utf8'));
+
+    const validTranslations = Object.keys(translations).filter((key) => {
+        if (key === '') { // metadata object added by gettext.js
+            return true;
+        }
+
+        const placeHolders = key.match(/{{.+?}}/g);
+
+        return (Array.isArray(translations[key]) ? translations[key] : [translations[key]]).every(
+            (translatedString) => {
+                const translatedStringWithoutPlaceholders = (placeHolders || []).reduce((acc, item) => {
+                    return acc.replace(item, '');
+                }, translatedString);
+
+                const valid = translatedStringWithoutPlaceholders.match(/{{.+?}}/) == null;
+
+                if (valid !== true) {
+                    grunt.log.error(
+                        `Invalid translation string encountered in "${filename}"`
+                        + ` and will be ommited from JSON: "${translatedString}"`
+                    );
+                }
+
+                return valid;
+            }
+        );
+    }).reduce((acc, key) => {
+        acc[key] = translations[key];
+
+        return acc;
+    }, {});
+
+    fs.writeFileSync(jsonFilePath, JSON.stringify(validTranslations), 'utf8');
+}
+
 function compileTranslationsPoToJson(grunt) {
     const currentDir = process.cwd();
     const clientCoreRoot = path.join(__dirname, '../');
@@ -41,6 +91,8 @@ function compileTranslationsPoToJson(grunt) {
             `${po2json} ${poFile} ${jsonFile}`,
             {stdio: 'inherit'}
         );
+
+        removeInvalidTranslations(grunt, jsonFile, filename);
     });
 }