React.jsの知っておいて損はないTips ref: http://qiita.com/endam/items/1bde821c4b29f9b663da

file0.txt

// エラーになる
render(){
  return(
    <div>aaa</div>
    <div>bbb</div>
  );
}

// 正常
render(){
  return(
    <div>
      <div>aaa</div>
      <div>bbb</div>
    </div>
  );
}

file1.txt

render() {
  if (!this.props.isShow) {
    return null; // もしくはreturn false;
  }
  return (
      <div>
        表示します
      </div>
  );
}

file10.txt

<div className="header {showClass}">

file11.txt

const headerClass = "header " + (isShow ? "show" : "hide"); 

...

<div className={headerClass}>

file12.txt

<div className={`header ${isShow ? "show" : "hide"}`}>

file2.txt

render() {
  const label = this.props.isShow ? <div>テスト</div> : null;
  const commentNodes = this.props.data.map((comment) => {
    return (
      <Comment author={comment.author}>
        {comment.text}
      </Comment>
    );
  });
  return (
    <div>
      {label}
      <div className="commentList">
        {commentNodes}
      </div>
    </div>
  );
}

file3.txt

render() {
  return (
    <div className="commentList">
      {(() => {
        if (this.props.isShow) {
          return <div>テスト</div>;
        }
      })()}
      {(() => {
        return (
          this.props.data.map((comment)=> {
            return <Comment author={comment.author}>
              {comment.text}
            </Comment>
          })
        );
      })()}
    </div>
  );
}

file4.txt

render() {
  return (
    <div className="commentList">
      {this.props.isShow && <div>テスト</div>}
      {this.props.data.map((comment)=> {
          return (
            <Comment author={comment.author}>
              {comment.text}
            </Comment>
          );
      })}
    </div>
  );
}

file5.txt

{this.props.isShow && <div>テスト</div>}

file6.txt

{this.props.isShow ? <div>テスト</div> : null}

file7.txt

onKeyPress(e) {
  console.log(`onKeyPress KeyCode:${e.charCode}`)
}

onKeyDown(e) {
  console.log(`onKeyDown KeyCode:${e.keyCode}`)
}

onKeyUp(e) {
  console.log(`onKeyUp KeyCode:${e.keyCode}`)
}


render() {
  return (
      <div>
        <form onSubmit={this.onSubmit}>
          <input type="text" onKeyDown={this.onKeyDown} onKeyPress={this.onKeyPress} onKeyUp={this.onKeyUp}/>
          <button type="submit">登録</button>
        </form>
      </div>
  );
}

file8.txt

<div className="header">

file9.txt

<div className={showClass}>