Property accessing in Javascript

utils.js

var utils = (function() {
    var utils = {},
        PROPERTY_REGEXP = /^(([a-z_][a-z0-9_]*\.?)+[a-z0-9_]+)$/i;
        
    var checkProperty = function(propName) {
        if(!PROPERTY_REGEXP.test(propName))
            throw new Error('Property ' + propName + ' misspelled');
        return propName;
    };
    
    utils.getProperty = function(obj, propName) {
        var props = checkProperty(propName).split('.'),
            current = obj;
        try {
            for(var i in props) {
                current = current[props[i]];
            }
        } catch(e) {
            throw new Error('Cannot read property ' + propName + ' of ' + JSON.stringify(obj, null, '\t'));
        }
        return current;
    }
    
    utils.setProperty = function(obj, propName, value) {
        var props = checkProperty(propName).split('.'),
            propToSet = props.pop(),
            current = utils.getProperty(obj, props.join('.'));
        current[propToSet] = value;
        return obj;        
    }
    return utils;
})();

var a = {"id":null,"caracteristique":{"datePrevue":"2014-11-01T01:00:00.000Z","dateReelle":null,"montantDepense":0,"solde":"0 €","dateDebutPeriode":null,"dateFinPeriode":null,"commentaire":null},"attributaire":{"attributaire":{"attributaire":null,"critereIndividu":null,"moyenPaiement":null,"critereMoyenPaiement":null}},"evenementComptable":{"listeEvenementComptable":{"options":{"data":[],"schema":{"model":{"id":"id","fields":{"id":{"type":"number","name":"id"},"montant":{"type":"string","name":"montant"},"evenement":{"type":"string","name":"evenement"},"date":{"type":"date","name":"date"},"reference":{"type":"string","name":"reference"},"autreInformation":{"type":"string","name":"autreInformation"}}}},"serverSorting":false,"serverPaging":false,"serverFiltering":false,"serverGrouping":false,"serverAggregates":false,"batch":false,"pageSize":5},"_map":{},"_prefetch":{},"_data":[],"_pristineData":[],"_ranges":[{"start":0,"end":0,"data":[]}],"_view":[],"_pristineTotal":0,"_destroyed":[],"_pageSize":5,"_page":1,"_group":[],"_total":0,"_events":{"change":[null,null,null,null,null,null,null,null],"progress":[null],"error":[null]},"transport":{"data":[]},"reader":{},"table":null,"_skip":0,"_take":5,"_requestInProgress":false,"_aggregateResult":{}}}};

a.aze;

console.log(utils.getProperty(a, 'caracteristique'));
console.log(utils.getProperty(a, 'caracteristique.montantDepense'));
console.log(utils.setProperty(a, 'caracteristique.montantDepense', 10));