User:Base/Scripts/RenameCertainUserContribs.js

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const api = new mw.Api();
const reason = 'Renaming translations with incorrect language code';
const namespace = 1198;
const user = 'Aamrs';
const startDate = '2019-01-06T18:00:00.000Z';
const wrongLanguage = 'en-gb';
const correctLanguage = 'pt';

api.get({
        action: 'query',
        meta: 'tokens'
    }).done((data) => {
            console.log(data);
            const token = data.query.tokens.csrftoken;

            api.get({
                action: 'query',
                list: 'usercontribs',
                ucuser: user,
                ucstart: startDate,
                ucnamespace: namespace,
                ucdir: 'newer',
                uclimit: 'max'
            }).done((data) => {
            	const dataToProceed = data.query.usercontribs.filter(item => item.title.endsWith('/' + wrongLanguage));

            	dataToProceed.forEach(item => {
            		const pageFrom = item.title;
            		const pageTo = pageFrom.replace(new RegExp(`/${wrongLanguage}$`), '/' + correctLanguage);

            		api.post({
                        action: 'move',
                        from: pageFrom,
                        to: pageTo,
                        reason: reason,
                        token: token,
                        noredirect: 1
                    }).done((data) => {
                        console.log(pageFrom + ' must has been moved to ' + pageTo);
                    });
            	});
            });
        });