等待渲染Reactjs时如何放置负载

Question

I just made an animated "loading.." using css but i want it to only exist when it's waiting for data to load/render.. any idea how I really dont know how im so new to this?...

this is my componentdidmount

componentDidMount() {
  $.ajax({
  url:'http://localhost:5118/api/employeedetails/getemployeedetails/',
  success:(data)=>{

    this.setState({
      jsonReturnedValue:data
    })
  }
})
  this.setState({isLoading: false})   
}

this is my render

renderItem(d, i) {
  return <tr key={i} >
    <td> {d.Employee_ID} </td>
    <td>{d.Employee_Name}</td>
    <td>{d.Address }</td> 
    <td><center><button className ="btn btn-info" onClick={this.handleOnclick.bind(this,  d.Employee_ID, d.Employee_Name, d.Address , d.Department , i)}   data-toggle="modal" data-target="#UpdateEmployee">Edit</button></center></td>
    <td><center><button className ='btn btn-danger'  onClick={this.handleOnclick2.bind (this,d.Employee_ID,d.Employee_Name,i)} data-toggle="modal" data-target="#DeleteEmployee"> Delete</button></center></td>
    </tr>
}

render() {
      if(this.state.isLoading) {
           return <span className="Loader">
          <div className="Loader-indicator" >
            <h1>
              <span>Loading</span>
              <span className="Loader-ellipsis" >
                <span className="Loader-ellipsisDot">.</span>
                <span className="Loader-ellipsisDot">.</span>
                <span className="Loader-ellipsisDot">.</span>
              </span>
            </h1>
          </div>
        </span>
     }

    let {jsonReturnedValue} = this.state;
    const isEnabled = this.canBeSubmitted();


  return(
    <div>
    <div>

        <div className="container">   
          <h1> Listof Employees </h1>
            <button className ='btn btn-warning right ' data-toggle="modal" data-target="#AddEmployee"> Add an Employee</button>
             <table className= "table table-bordered" id="result"> 
                <tbody>
                 <tr>
                      <th>ID</th>
                      <th>Name</th>
                      <th>Address</th>
                      <th>Update</th>
                      <th>Delete</th>
                 </tr>
                    {jsonReturnedValue.map((d,i) => this.renderItem(d,i))}
                </tbody>

            </table>
          </div>

Answer 1

Maintain a state in your react component that is set to true whenever you give a call to load the data

Eg

class App extends React.Component {
     constructor(){
         super();
         this.state = {isLoading: true}
     }


componentDidMount() {


   $.ajax({
      url:'http://localhost:5118/api/employeedetails/getemployeedetails/',
      success:(data)=>{ 
        this.setState({
           jsonReturnedValue:data, isLoading: false
        })
      }
   })

}

render() {
     if(this.state.isLoading) {
           return <span className="Loader">
          <div className="Loader-indicator" >
            <h1>
              <span>Loading</span>
              <span className="Loader-ellipsis" >
                <span className="Loader-ellipsisDot">.</span>
                <span className="Loader-ellipsisDot">.</span>
                <span className="Loader-ellipsisDot">.</span>
              </span>
            </h1>
          </div>
        </span>
     }
     return (
         <div>Hello World</div>
     )

}

See a demo snippet

 class App extends React.Component { constructor(){ super(); this.state = {isLoading: true} } componentDidMount() { setTimeout(() => {this.setState({isLoading: false})}, 3000) } render() { if(this.state.isLoading) { return <span className="Loader"> <div className="Loader-indicator" > <h1> <span>Loading</span> <span className="Loader-ellipsis" > <span className="Loader-ellipsisDot">.</span> <span className="Loader-ellipsisDot">.</span> <span className="Loader-ellipsisDot">.</span> </span> </h1> </div> </span> } return ( <div>Hello World</div> ) } } ReactDOM.render(<App/>, document.getElementById('app')); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script> <div id="app"></div> 

Answer 2

add loading state, and make it true, when data is loaded.

in render() function make add loading state code, using ? operator.

{this.state.loading ? (<YourComponent />) : (<LoadingState />)}

replace <YourComponent /> and <LoadingState /> with your component or needed jsx tags...