JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.3.2/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.3.2/react-dom.js"></script>
<div id="app"></div>

Babel + JSX

var MyCom = React.createClass({
  getInitialState: function() {
    return {
      random: 'lorem',
      letters:[]
    }
  },
  splitLetter:function(){
   var s = this.state.random;
   for (var i = 0; i < s.length; i++) {
    this.state.letters.push(s.charAt(i));
   }
   this.setState({
   letters:this.state.letters
   })
  },
  getLetter:function(e){
   var val = e.currentTarget.textContent;
    this.state.letters.forEach(function(letter) {
     if (letter === val) {
     alert("There is 'r' letter in the word.")
     e.target.className = 'clicked';
     letter.className='foundedLetter';
    }
});
  },
  render: function() {
    return (
      <div>
      <p>The word is: <strong>{this.state.random}</strong></p>
      <p>Click the button first then click the r letter below</p>
        <button onClick={this.splitLetter}>Split letter</button>
        <p>Click on: <strong><span onClick={this.getLetter}>r</span></strong></p>
      {this.state.letters.map(function(item){
     return (
       <div>
         <span>{item}</span>  
      </div>
       )
    },this) /*added this to map function  */
    }
    </div>
    )
  }
});

ReactDOM.render(
  <MyCom/>,
  document.getElementById("app")
)