1.e.preventdefault() 

2.

<form action="#" ref="form" target="testif" onSubmit={this.submit}>

<label htmlFor="title">ToDoList</label>

<input type="text" ref="title" name="title" placeholder="添加ToDo" required="required" autoComplete="off" />>

<iframe name="testif" style={

{ "display": "none" }}></iframe>

</form>