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React - uncaught TypeError: Cannot read property 'setState' of undefined

Full error message

I am getting the following error

  Uncaught TypeError: Cannot read property 'setState' of undefined

even after binding delta in the constructor.

class Counter extends React.Component {
    constructor(props) {
        super(props);

        this.state = {
            count : 1
        };

        this.delta.bind(this);
    }

    delta() {
        this.setState({
            count : this.state.count++
        });
    }

    render() {
        return (
            <div>
                <h1>{this.state.count}</h1>
                <button onClick={this.delta}>+</button>
            </div>
        );
    }
}

Solutionsource: stackoverflow \u2197

This is due to this.delta not being bound to this. Option A: In order to bind set this.delta = this.delta.bind(this) in the constructor: constructor(props) { super(props); this.state = { count : 1 }; this.delta = this.delta.bind(this); } Currently, you are calling bind. But bind returns a bound function. You need to set the function to its bound value. Option B: Use an arrow function: constructor(props) { super(props); this.state = { count : 1 }; } delta = ()=> { this.setState({ count : this.state.count++ }); }

API access

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hash \u00b7 e0120e86055568cd6ca19d4d5f80c9374c87808b08d2c2eb937e68e6941698e3

React - uncaught TypeError: Cannot read property &#39;setState&#39; of undefined

React - uncaught TypeError: Cannot read property 'setState' of undefined