Clear an input field with Reactjs?

Declare value attribute for input tag (i.e value= {this.state.name}) and if you want to clear this input value you have to use this.setState({name : ''})

PFB working code for your reference :

<script type="text/babel">
    var StateComponent = React.createClass({
        resetName : function(event){
            this.setState({
                name : ''
            });
        },
        render : function(){
            return (
                <div>
                    <input type="text" value= {this.state.name}/>
                    <button onClick={this.resetName}>Reset</button>
                </div>
            )
        }
    });
    ReactDOM.render(<StateComponent/>, document.getElementById('app'));
</script>

I'm not really sure of the syntax {el => this.inputEntry = el}, but when clearing an input field you assign a ref like you mentioned.

<input type="text" ref="someName" />

Then in the onClick function after you've finished using the input value, just use...

this.refs.someName.value = '';

Edit

Actually the {el => this.inputEntry = el} is the same as this I believe. Maybe someone can correct me. The value for el must be getting passed in from somewhere, to act as the reference.

function (el) {
    this.inputEntry = el;
}

Let me assume that you have done the 'this' binding of 'sendThru' function.

The below functions clears the input fields when the method is triggered.

sendThru() {
    this.inputTitle.value = "";
    this.inputEntry.value = "";
}

Refs can be written as inline function expression:

ref={el => this.inputTitle = el}

where el refers to the component.

When refs are written like above, React sees a different function object each time so on every update, ref will be called with null immediately before it's called with the component instance.

Read more about it here.