TypeError 'x' is not a function : <p>TypeError: this.props.handleClick is not a function</p>

<pre><code>class Task extends React.Component{

    render(){
        return(
            &lt;div className="Task"&gt;
                &lt;span style = {{ textDecoration : this.props.todo.done ? 'line-through' : 'none'}}&gt;{this.props.todo.value}&lt;/span&gt; 
                &lt;button onClick = {() =&gt; this.props.handleClick(this.props.index)}&gt;{this.props.todo.done ? 'Undo' : 'Complete'}&lt;/button&gt;
            &lt;/div&gt;
        )
    }
}
</code></pre>
