Updating State in React Component with TypeScript and JSX

React Event Handlers with Typescript and JSX

If you’re working with React and Typescript, you may encounter issues when trying to update state in your React components. In this blog post, we will explore how to troubleshoot and resolve these problems by using event handlers in the context of React and Typescript with JSX.

Problem Analysis: Updating State in React Component

When working with React components in Typescript, updating state can sometimes be a challenge. In the provided code snippet, two event handlers, handleClick and handleChange, are not updating the state correctly. The values for this indicate that the state object is not available, resulting in unexpected behavior.

Solution 1: Binding Methods with “this”

In React components created using the class syntax, you need to manually bind the methods with the component instance by using the bind method. By binding the methods, you ensure that the correct instance of the component is referenced within the event handlers.

class Tester extends React.Component<any, TestState> {
  constructor(props) {
    super(props);
    this.state = { liked: false, name: "Anders" };
    this.handleClick = this.handleClick.bind(this);
    this.handleChange = this.handleChange.bind(this);
  }

  handleClick(evt, domNode): void {
    this.setState({ liked: !this.state.liked, name: this.state.name });
  }

  handleChange(evt, a, b, c): void {
    this.setState({ liked: this.state.liked, name: evt.target.value });
  }

  //...
}

Solution 2: Binding Methods Directly in the Render Method

An alternative approach is to bind the methods directly in the render method. By doing so, you avoid the need for additional constructor code. However, it is important to note that this will create a new function instance on each render, which may impact performance if used excessively.

render() {
  var text = this.state.liked ? "liked " : "haven't liked ";
  return (
    <div>
      You {text} {this.state.name} 
      <button onClick={this.handleClick.bind(this)}>Like</button>
      <input value={this.state.name} onChange={this.handleChange.bind(this)} />
    </div>
  );
}

Solution 3: Fat Arrow Functions for Event Handlers

Another approach to automatically bind the correct instance of the component is by using fat arrow functions for the event handlers. Fat arrow functions capture the lexical scope of this, eliminating the need for manual binding.

handleClick = (evt, domNode):void => {
  this.setState({ liked: !this.state.liked, name: this.state.name });
};

render() {
  //...
  return (
    <div>
      //...
      <button onClick={() => this.handleClick()}>Like</button>
      //...
    </div>
  );
}

Conclusion

In this blog post, we discussed how to troubleshoot and resolve state updating issues in React components written with Typescript and JSX. By binding the event handler methods with the component instance, either through the constructor or directly in the render method, we ensure that the state is updated correctly.

By understanding the various methods available to bind the correct instance of this, you can confidently handle event-driven interactions in your React components, providing a smooth and predictable user experience.

Remember to choose the method that best suits your specific project requirements and ensure the efficient utilization of resources to achieve optimal performance.

reference : 

reactjs