我目前在React.JS中具有此组件，该组件以数组形式显示传递给它的所有图像，而onMouseOver则在下面显示一个按钮。我计划使用setState检查变量悬停是否为true或false并相应地切换该图像的按钮，但是我不断收到以下错误：

未捕获的TypeError：无法读取未定义的属性“状态”

var ImageList = React.createClass({
getInitialState: function () {
    return this.state = { hover: false };
},
getComponent: function(index){
      console.log(index);
      if (confirm('Are you sure you want to delete this image?')) {
          // Save it!
      } else {
          // Do nothing!
      }    
},
mouseOver: function () {
    this.setState({hover: true});
    console.log(1);
},

mouseOut: function () {
    this.setState({hover: false});
    console.log(2);
},
render: function() {
var results = this.props.data,
  that = this;
return (
  <ul className="small-block-grid-2 large-block-grid-4">
    {results.map(function(result) {
      return(
              <li key={result.id} onMouseOver={that.mouseOver} onMouseOut={that.mouseOut} ><img className="th" alt="Embedded Image" src={"data:" + result.type + ";"  + "base64," + result.image} /> <button onClick={that.getComponent.bind(that, result.patientproblemimageid)} className={(this.state.hover) ? 'button round button-center btshow' : 'button round button-center bthide'}>Delete Image</button></li>
      )      
    })}
  </ul>
);
}

});