Private state in React Components

UsernameField.js

let UsernameField = (() => {
  const _username = Symbol();
  const _handleNameChange = Symbol();
  
  return class UsernameField extends React.Component {
    state = {
      [_username]: 'DefaultUser',
    }
    
    [_handleNameChange] = (e) => {
      this.setState({
        [_username]: e.target.value,
      });
    }
    
    render() {
      return (
        <input
          value={this.state[_username]}
          onChange={this[_handleNameChange]}
        />
      );
    }
  }
})();

UsernameField.min.js

// UsernameField.js babel-transpiled, uglified then beautified
"use strict";

var UsernameField = function() {
    var e = Symbol(), t = Symbol();
    return function(r) {
        function n() {
            var r = this;
            _classCallCheck(this, n), _get(Object.getPrototypeOf(n.prototype), "constructor", this).apply(this, arguments), 
            this.state = _defineProperty({}, e, "DefaultUser")[t] = function(t) {
                r.setState(_defineProperty({}, e, t.target.value));
            };
        }
        return _inherits(n, r), _createClass(n, [ {
            key: "render",
            value: function() {
                return React.createElement("input", {
                    value: this.state[e],
                    onChange: this[t]
                });
            }
        } ]), n;
    }(React.Component);
}();