javascript - Rendering React Components from Array of Objects

Question

I have some data called stations which is an array containing objects.

stations : [
  {call:'station one',frequency:'000'},
  {call:'station two',frequency:'001'}
]

I'd like to render a ui component for each array position. So far I can write

 var stationsArr = []
 for (var i = 0; i < this.data.stations.length; i++) {
     stationsArr.push(
         <div className="station">
             {this.data}
         </div>
     )
 }

And then render

render(){
 return (
   {stationsArr}
 )
}

The problem is I'm getting all of the data printing out. I instead want to just show a key like {this.data.call} but that prints nothing.

How can I loop through this data and return a new UI element for each position of the array?

Answer 1

You can map the list of stations to ReactElements.

With React >= 16, it is possible to return multiple elements from the same component without needing an extra html element wrapper. Since 16.2, there is a new syntax <> to create fragments. If this does not work or is not supported by your IDE, you can use <React.Fragment> instead. Between 16.0 and 16.2, you can use a very simple polyfill for fragments.

Try the following

// Modern syntax >= React 16.2.0
const Test = ({stations}) => (
  <>
    {stations.map(station => (
      <div key={station.call} className='station'>{station.call}</div>
    ))}
  </>
); 

// Modern syntax < React 16.2.0
// You need to wrap in an extra element like div here

const Test = ({stations}) => (
  <div>
    {stations.map(station => (
      <div className="station" key={station.call}>{station.call}</div>
    ))}
  </div>
); 

// old syntax
var Test = React.createClass({
    render: function() {
        var stationComponents = this.props.stations.map(function(station) {
            return <div className="station" key={station.call}>{station.call}</div>;
        });
        return <div>{stationComponents}</div>;
    }
});
 
var stations = [
  {call:'station one',frequency:'000'},
  {call:'station two',frequency:'001'}
]; 

ReactDOM.render(
  <div>
    <Test stations={stations} />
  </div>,
  document.getElementById('container')
);

Don't forget the key attribute!

https://jsfiddle.net/69z2wepo/14377/