React

HTML

<div id="app"></div>

CSS

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

#app {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  transition: all 0.2s;
}

li {
  margin: 8px 0;
}

h2 {
  font-weight: bold;
  margin-bottom: 15px;
}

.done {
  color: rgba(0, 0, 0, 0.3);
  text-decoration: line-through;
}

input {
  margin-right: 5px;
}

React

class TodoApp extends React.Component {
  constructor(props) {
    super(props)
    this.state = {
    	students: [
      	['a', 'b', 'c', 'd'],
      	['a', 'b', 'c', 'd']
      ]
    }
  }
  
  render() {
    return (<table className="table-data">
 <tbody>
 <tr>
    <th>Name</th>
    <th>Age</th>
    <th>Class</th>
    <th>Section</th>
 </tr>   
 
 {  this.state.students.map((item,key) => {

    const editField = (value, index) => {

      // Clone students data before mutation
      const students = this.state.students.map(item => ({ ...item }))

      // Update field by index of current student
      students[key][index] = value

      // Trigger re-render
      this.setState({ students })
    }

   return (
    <tr key={key} className={ item.editing ? 'editing' : '' } onClick={()=> {

      // Clone students data before mutation
      const students = this.state.students.map(i => ({ ...i, editing : item.editing && i===item }))

      // Toggle editing flag of this current student (ie table row)
      students[key].editing = true; 

      // Trigger re-render
      this.setState({
        clientIsEditing:true, // This might not be needed ?
        students
      })
}
    }> 
    <td>{ item.editing ? <input value={item[1]} onChange={ e => editField(e.target.value, 1) } /> : <span>{item[1]}</span> }</td>    
    <td>{ item.editing ? <input value={item[2]} onChange={ e => editField(e.target.value, 2) } /> : <span>{item[2]}</span> }</td>    
    <td>{ item.editing ? <input value={item[3]} onChange={ e => editField(e.target.value, 3) } /> : <span>{item[3]}</span> }</td>  
    <td>{ item.editing ? <input value={item[4]} onChange={ e => editField(e.target.value, 4) } /> : <span>{item[4]}</span> }</td> 
    </tr>  )
  })
  }
  
  </tbody>
  </table>)
  }
}

ReactDOM.render(<TodoApp />, document.querySelector("#app"))