javascript - 不从 React 中的函数渲染 JSX

Question

该函数获取按钮点击的值作为 Prop 。映射数据以将该按钮值与数据 JSON 中称为“类”的键进行比较。我正在正确获取所有数据。我所有的 console.logs 都返回正确的值。但出于某种原因，我无法渲染任何东西。

我尝试添加两个返回语句。它甚至没有呈现带有“TEST”一词的 p 标签。我错过了什么吗？我已经包含了一个代码沙箱:https://codesandbox.io/s/react-example-8xxih

例如，当我单击“数学”按钮时，我想将教数学的两位老师显示为按钮下方的两个气泡。 所有数据正在加载。只是在渲染时遇到问题。

function ShowBubbles(props){
    console.log('VALUE', props.target.value)
   return (
       <div id='bubbles-container'>
          <p>TEST</p> 
       {Data.map((item,index) =>{
        if(props.target.value == (Data[index].classes)){
          return (
               <Bubble key={index} nodeName={Data[index].name}>{Data[index].name}
              </Bubble>    
          )

        }
    })}
    </div>
   )
}

Answer 1

沙盒链接:https://codesandbox.io/embed/react-example-m1880

import React, {Component} from 'react';
import ReactDOM from 'react-dom';
const circleStyle = {
  width: 100,
  height: 100,
  borderRadius: 50,
  fontSize: 30,
  color: "blue"
};

const Data = [
  {
    classes: ["Math"],
    name: "Mr.Rockow",
    id: "135"
  },
  {
    classes: ["English"],
    name: "Mrs.Nicastro",
    id: "358"
  },
  {
    classes: ["Chemistry"],
    name: "Mr.Bloomberg",
    id: "405"
  },
  {
    classes: ["Math"],
    name: "Mr.Jennings",
    id: "293"
  }
];

const Bubble = item => {
  let {name} = item.children.singleItem;
  return (
    <div style={circleStyle} onClick={()=>{console.log(name)}}>
      <p>{item.children.singleItem.name}</p>
    </div>
  );
};

function ShowBubbles(props) {
  var final = [];
  Data.map((item, index) => {
    if (props.target.value == Data[index].classes) {
      final.push(Data[index])
    }
  })
  return final;
}

function DisplayBubbles(singleItem) {
  return <Bubble>{singleItem}</Bubble>
}

class Sidebar extends Component {
  constructor(props) {
    super(props);

    this.state = {
      json: [],
      classesArray: [],
      displayBubble: true
    };
    this.showNode = this.showNode.bind(this);
  }

  componentDidMount() {
    const newArray = [];
    Data.map((item, index) => {
      let classPlaceholder = Data[index].classes.toString();
      if (newArray.indexOf(classPlaceholder) == -1) {
        newArray.push(classPlaceholder);
      }
      // console.log('newArray', newArray)
    });
    this.setState({
      json: Data,
      classesArray: newArray
    });
  }

  showNode(props) {
    this.setState({
      displayBubble: true
    });

    if (this.state.displayBubble === true) {
      var output = ShowBubbles(props);
      this.setState({output})
    }
  }
  render() {
    return (
      <div>
        {/* {this.state.displayBubble ? <ShowBubbles/> : ''}  */}

        <div id="sidebar-container">
          <h1 className="sidebar-title">Classes At School</h1>

          <h3>Classes To Search</h3>

          {this.state.classesArray.map((item, index) => {
            return (
              <button
                onClick={this.showNode}
                className="btn-sidebar"
                key={index}
                value={this.state.classesArray[index]}
              >
                {this.state.classesArray[index]}
              </button>
            );
          })}
        </div>
        {this.state.output && this.state.output.map(item=><DisplayBubbles singleItem={item}/>)}
      </div>
    );
  }
}

ReactDOM.render(<Sidebar />, document.getElementById("root"));

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.0.0/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.0.0/umd/react-dom.production.min.js"></script>
<div id="root"></div>