我有一个React组件,在组件的渲染方法中,我有这样的东西:

render() {
    return (
        <div>
            <div>
                // removed for brevity
            </div>

           { switch(...) {} }

            <div>
                // removed for brevity
            </div>
        </div>
    );
}

Now the point is that I have two div elements, one at the top and one at the bottom, that are fixed. In the middle I want to have a switch statement, and according to a value in my state I want to render a different component. So basically, I want the two div elements to be fixed always, and just in the middle to render a different component each time. I'm using this to implement a multi-step payment procedure). Though, as is the code currently it doesn't work, as it gives me an error saying that switch is unexpected. Any ideas how to achieve what I want?


当前回答

下面是一个使用按钮在组件之间切换的完整工作示例

可以按如下方式设置构造函数

constructor(props)
{
    super(props);
    this.state={
        currentView: ''
    }
}

然后您就可以像下面这样渲染组件了

  render() 
{
    const switchView = () => {

    switch(this.state.currentView) 
    {

      case "settings":   return <h2>settings</h2>;
      case "dashboard":   return <h2>dashboard</h2>;

      default:      return <h2>dashboard</h2>
    }
  }

    return (

       <div>

            <button onClick={(e) => this.setState({currentView: "settings"})}>settings</button>
            <button onClick={(e) => this.setState({currentView: "dashboard"})}>dashboard</button>

            <div className="container">
                { switchView() }
            </div>


        </div>
    );
}

}

正如你所看到的,我正在使用一个按钮来切换状态。

其他回答

你可以这样做。

 <div>
          { object.map((item, index) => this.getComponent(item, index)) }
 </div>

getComponent(item, index) {
    switch (item.type) {
      case '1':
        return <Comp1/>
      case '2':
        return <Comp2/>
      case '3':
        return <Comp3 />
    }
  }

我在render()方法中做了这个:

  render() {
    const project = () => {
      switch(this.projectName) {

        case "one":   return <ComponentA />;
        case "two":   return <ComponentB />;
        case "three": return <ComponentC />;
        case "four":  return <ComponentD />;

        default:      return <h1>No project match</h1>
      }
    }

    return (
      <div>{ project() }</div>
    )
  }

我试图保持render()返回干净,所以我把我的逻辑放在一个'const'函数上面。这样我也可以缩进我的开关盒整齐。

试试这个,它也更干净:在一个函数中获得渲染的开关,并调用它传递你想要的参数。例如:

renderSwitch(param) {
  switch(param) {
    case 'foo':
      return 'bar';
    default:
      return 'foo';
  }
}

render() {
  return (
    <div>
      <div>
          // removed for brevity
      </div>
      {this.renderSwitch(param)}
      <div>
          // removed for brevity
      </div>
    </div>
  );
}
import React from 'react';

import ListView from './ListView';
import TableView from './TableView';

function DataView({
    currView,
    data,
    onSelect,
    onChangeStatus,
    viewTodo,
    editTodo,
    deleteTodo,
}) {
    return (
        <div>
            {(function () {
                switch (currView) {
                    case 'table':
                        return (
                            <TableView
                                todos={data}
                                onSelect={onSelect}
                                onChangeStatus={onChangeStatus}
                                viewTodo={viewTodo}
                                editTodo={editTodo}
                                deleteTodo={deleteTodo}
                            />
                        );

                    case 'list':
                        return (
                            <ListView
                                todos={data}
                                onSelect={onSelect}
                                onChangeStatus={onChangeStatus}
                                viewTodo={viewTodo}
                                editTodo={editTodo}
                                deleteTodo={deleteTodo}
                            />
                        );

                    default:
                        break;
                }
            })()}
        </div>
    );
}

export default DataView;

这个答案专门用来解决@tonyfat提出的“重复”问题,关于如何使用条件表达式来处理相同的任务。


Avoiding statements here seems like more trouble than it's worth, but this script does the job as the snippet demonstrates:

// Runs tests let id = 0, flag = 0; renderByFlag(id, flag); // jobId out of range id = 1; // jobId in range while(++flag < 5){ // active flag ranges from 1 to 4 renderByFlag(id, flag); } // Defines a function that chooses what to render based on two provided values function renderByFlag(jobId, activeFlag){ jobId === 1 ? ( activeFlag === 1 ? render("A (flag = 1)") : activeFlag === 2 ? render("B (flag = 2)") : activeFlag === 3 ? render("C (flag = 3)") : pass(`flag ${activeFlag} out of range`) ) : pass(`jobId ${jobId} out of range`) } // Defines logging functions for demo purposes function render(val){ console.log(`Rendering ${val}`); } function pass(reason){ console.log(`Doing nothing (${reason})`) }