Dropdown cascading fetch the selected value

A few things need to be fixed;

  1. You need to keep a state value for the selected server selectserver.
    this.state = {
      ...
      selectserver: "",
      ...
    };
  1. The routeChange handler function should update selectserver.
  routeChange = (e) => {
    this.setState({ selectserver: e.target.value });
  };
  1. Server selection need to to this.state.selectserver as the value.
<select
     value={this.state.selectserver}
     onChange={this.routeChange}
>
  ...
  ...
</select>

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