Code:
        Ext.define('MyModel', {
                extend: 'Ext.data.Model',
                fields: [
                        {name: '12345',  type: 'string'}
                ],
                proxy: {
                        type: 'memory'
                }
        });

        var reader = Ext.create('Ext.data.JsonReader', {
                model: 'MyModel',
                root: 'root'
        });

        var recs = reader.readRecords({
                root: [{
                        '12345': 'field 1 value'
                }]
        });

        alert(recs.records[0].get('12345'));
Code:
SyntaxError: Expected an identifier but found '=' instead