小tip：label-for以及dangerouslySetIn

<Fragment>
        <div>
          <label htmlFor="insertArea">input value</label>
          <input 
            value={this.state.inputValue}
            id="insertArea"
            className='input'
            onChange={this.handleInputChange.bind(this)}/>
          <button onClick={this.handleBtnClick.bind(this)}>submit</button>
        </div>
        <ul>
          {
            this.state.list.map((item, index) => {
              return <li key={index} 
                         onClick={this.handleItemDelete.bind(this, index)}
                         dangerouslySetInnerHTML={{__html: item}}
                     >                      
                     </li>
            })
          }
        </ul>
      </Fragment>

label中的聚焦使用，htmlFor(id)
dangerouslySetInnerHTML，网页显示语义化标签