var json2json = require('node-json2json');
    
    var data = {'c:areaChart':{'needthis':{'propArea':'value'},'dontneedthis':{}},
            'c:pieChart':{'needthis':{'propPie':'value'},'dontneedthis':{}}};
 
    var transform = {'$[var=c:(.+)Chart]':'','chart':'$(var)','stuff':'${c:$(var)Chart.needthis}'};
        
    console.log( json2json.transform(data,transform) );