$re = '/((var|const|let)\s+)?[A-Za-z0-9_\.\[\]"\']+\s?=\s+?{/';
$str = 'acf0.data = {"select2L10n":{"matches_1":"Es ist ein Ergebnis verf\\u00fcgbar, dr\\u00fccke die Eingabetaste um es auszuw\\u00e4hlen.","matches_n":"Es sind %d Ergebnisse verf\\u00fcgbar, benutze die Pfeiltasten um nach oben und unten zu navigieren.","matches_0":"Keine \\u00dcbereinstimmungen gefunden","input_too_short_1":"Gib bitte ein oder mehr Zeichen ein","input_too_short_n":"Gib bitte %d oder mehr Zeichen ein","input_too_long_1":"L\\u00f6sche bitte ein Zeichen","input_too_long_n":"L\\u00f6sche bitte %d Zeichen","selection_too_long_1":"Du kannst nur ein Element ausw\\u00e4hlen","selection_too_long_n":"Du kannst nur %d Elemente ausw\\u00e4hlen","load_more":"Mehr Ergebnisse laden…","searching":"Suchen…","load_fail":"Laden fehlgeschlagen"},"google_map_api":"https:\\/\\/maps.googleapis.com\\/maps\\/api\\/js?key=AIzaSyDzJU4YaeA4XDHAN1BvFOZD8A2eF5lxYr0&libraries=places&ver=3&callback&language=de_DE","datePickerL10n":{"closeText":"Fertig","currentText":"Heute","nextText":"N\\u00e4chstes","prevText":"Vorheriges","weekHeader":"W","monthNames":["Januar","Februar","M\\u00e4rz","April","Mai","Juni","Juli","August","September","Oktober","November","Dezember"],"monthNamesShort":["Jan","Feb","Mrz","Apr","Mai","Jun","Jul","Aug","Sep","Okt","Nov","Dez"],"dayNames":["Sonntag","Montag","Dienstag","Mittwoch","Donnerstag","Freitag","Samstag"],"dayNamesMin":["S","M","D","M","D","F","S"],"dayNamesShort":["So","Mo","Di","Mi","Do","Fr","Sa"]},"dateTimePickerL10n":{"timeOnlyTitle":"Zeit ausw\\u00e4hlen","timeText":"Zeit","hourText":"Stunde","minuteText":"Minute","secondText":"Sekunde","millisecText":"Millisekunde","microsecText":"Mikrosekunde","timezoneText":"Zeitzone","currentText":"Jetzt","closeText":"Fertig","selectText":"Ausw\\u00e4hlen","amNames":["Vorm.","Vorm."],"pmNames":["Nachm.","Nachm."]},"colorPickerL10n":{"hex_string":"Hex String","rgba_string":"RGBA String"},"mimeTypeIcon":"https:\\/\\/wptest.photoclub-reutlingen.de\\/wp-includes\\/images\\/media\\/default.png","mimeTypes":{"jpg|jpeg|jpe":"image\\/jpeg","gif":"image\\/gif","png":"image\\/png","bmp":"image\\/bmp","tiff|tif":"image\\/tiff","webp":"image\\/webp","ico":"image\\/x-icon","heic":"image\\/heic","asf|asx":"video\\/x-ms-asf","wmv":"video\\/x-ms-wmv","wmx":"video\\/x-ms-wmx","wm":"video\\/x-ms-wm","avi":"video\\/avi","divx":"video\\/divx","flv":"video\\/x-flv","mov|qt":"video\\/quicktime","mpeg|mpg|mpe":"video\\/mpeg","mp4|m4v":"video\\/mp4","ogv":"video\\/ogg","webm":"video\\/webm","mkv":"video\\/x-matroska","3gp|3gpp":"video\\/3gpp","3g2|3gp2":"video\\/3gpp2","txt|asc|c|cc|h|srt":"text\\/plain","csv":"text\\/csv","tsv":"text\\/tab-separated-values","ics":"text\\/calendar","rtx":"text\\/richtext","css":"text\\/css","vtt":"text\\/vtt","dfxp":"application\\/ttaf+xml","mp3|m4a|m4b":"audio\\/mpeg","aac":"audio\\/aac","ra|ram":"audio\\/x-realaudio","wav":"audio\\/wav","ogg|oga":"audio\\/ogg","flac":"audio\\/flac","mid|midi":"audio\\/midi","wma":"audio\\/x-ms-wma","wax":"audio\\/x-ms-wax","mka":"audio\\/x-matroska","rtf":"application\\/rtf","pdf":"application\\/pdf","class":"application\\/java","tar":"application\\/x-tar","zip":"application\\/zip","gz|gzip":"application\\/x-gzip","rar":"application\\/rar","7z":"application\\/x-7z-compressed","psd":"application\\/octet-stream","xcf":"application\\/octet-stream","doc":"application\\/msword","pot|pps|ppt":"application\\/vnd.ms-powerpoint","wri":"application\\/vnd.ms-write","xla|xls|xlt|xlw":"application\\/vnd.ms-excel","mdb":"application\\/vnd.ms-access","mpp":"application\\/vnd.ms-project","docx":"application\\/vnd.openxmlformats-officedocument.wordprocessingml.document","docm":"application\\/vnd.ms-word.document.macroEnabled.12","dotx":"application\\/vnd.openxmlformats-officedocument.wordprocessingml.template","dotm":"application\\/vnd.ms-word.template.macroEnabled.12","xlsx":"application\\/vnd.openxmlformats-officedocument.spreadsheetml.sheet","xlsm":"application\\/vnd.ms-excel.sheet.macroEnabled.12","xlsb":"application\\/vnd.ms-excel.sheet.binary.macroEnabled.12","xltx":"application\\/vnd.openxmlformats-officedocument.spreadsheetml.template","xltm":"application\\/vnd.ms-excel.template.macroEnabled.12","xlam":"application\\/vnd.ms-excel.addin.macroEnabled.12","pptx":"application\\/vnd.openxmlformats-officedocument.presentationml.presentation","pptm":"application\\/vnd.ms-powerpoint.presentation.macroEnabled.12","ppsx":"application\\/vnd.openxmlformats-officedocument.presentationml.slideshow","ppsm":"application\\/vnd.ms-powerpoint.slideshow.macroEnabled.12","potx":"application\\/vnd.openxmlformats-officedocument.presentationml.template","potm":"application\\/vnd.ms-powerpoint.template.macroEnabled.12","ppam":"application\\/vnd.ms-powerpoint.addin.macroEnabled.12","sldx":"application\\/vnd.openxmlformats-officedocument.presentationml.slide","sldm":"application\\/vnd.ms-powerpoint.slide.macroEnabled.12","onetoc|onetoc2|onetmp|onepkg":"application\\/onenote","oxps":"application\\/oxps","xps":"application\\/vnd.ms-xpsdocument","odt":"application\\/vnd.oasis.opendocument.text","odp":"application\\/vnd.oasis.opendocument.presentation","ods":"application\\/vnd.oasis.opendocument.spreadsheet","odg":"application\\/vnd.oasis.opendocument.graphics","odc":"application\\/vnd.oasis.opendocument.chart","odb":"application\\/vnd.oasis.opendocument.database","odf":"application\\/vnd.oasis.opendocument.formula","wp|wpd":"application\\/wordperfect","key":"application\\/vnd.apple.keynote","numbers":"application\\/vnd.apple.numbers","pages":"application\\/vnd.apple.pages"},"toolbars":{"full":{"1":"formatselect,bold,italic,bullist,numlist,blockquote,alignleft,aligncenter,alignright,link,wp_more,spellchecker,fullscreen,wp_adv","2":"strikethrough,hr,forecolor,pastetext,removeformat,charmap,outdent,indent,undo,redo,wp_help","3":"","4":""},"basic":{"1":"bold,italic,underline,blockquote,strikethrough,bullist,numlist,alignleft,aligncenter,alignright,undo,redo,link,fullscreen"}},"admin_url":"https:\\/\\/wptest.photoclub-reutlingen.de\\/wp-admin\\/","ajaxurl":"https:\\/\\/wptest.photoclub-reutlingen.de\\/wp-admin\\/admin-ajax.php","nonce":"6f1ca57d8e","acf_version":"5.10.1","wp_version":"5.8.1","browser":"chrome","locale":"de_DE","rtl":false,"screen":null,"post_id":null,"validation":null,"editor":"classic"};
';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php