How to add a comma in array.map after every element except last element in React JSX

How can I add a trailing comma after every element of an array for making a list like:

INV, INV, INV, INV

Note that the last element doesn’t have a trailing comma

Currently iterating the list with array.map:

var List = React.createClass({
  render: function() {
    return (
      <div>
        {this.props.data.map(function(item) {
          return <div>{item}</div>;
        })}
      </div>
    );
  }
});

var data = ["red", "green", "blue"];

React.render(<List data={data} />, document.body);

Answer

As commented you can use:

array.map((item, index) => ({ (index ? ‘, ‘: ”) + item }))

Also, since you want to display text inline, using a div is not appropriate. Instead you can/should use an inline element like span

var List = React.createClass({
  render: function() {
    return (
      <div>
        {
          this.props.data.map(function(item, index) {
            return <span key={`demo_snap_${index}`}>{ (index ? ', ' : '') + item }</span>;
          })
        }
      </div>
    );
  }
});

var data = ["red", "green", "blue"];

ReactDOM.render(<List data={data} />, demo);
<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="demo"></div>