Event Handling is one of the important features of React. It is important to bind the event handlers with this keyword so that they can get the correct access to this keyword in the class component itself. In this blog, we will discuss the different ways through which we can bind event handlers with this. Various methods are:

Binding Within the constructor:

Let’s look at the example via code snippet.

This is the common approach where we use the constructor of the component class to bind the Event Handler. In the above example, increment is the event handler that is used to increase the counter whenever the button is clicked. To make sure that this keyword is used along the setState() method inside the increment method, we have bound the context of the event handler(increment) with the context of the class that is Hello so that it can get access to the “Hello” class only whenever increment method is called and change the state correctly. 

Therefore we bind the event handler within the constructor itself. Since we did the binding within the constructor, it will happen only once when the class is being initialized.

Defining event handler as an arrow function

This is another common way of binding event handlers with this.

We have used the same example but this time, we have bound inside the constructor but changed the event handler as an arrow function. Since arrow functions do not have their own context, it take the context of surroundings ensuring correct reference of this.  In this way, we can define event handlers as the class properties itself.

Calling the event Handler in JSX as an arrow function

This is the third way with which we can bind the context of this with the event handlers. 

In this method, we are using the event handler as an arrow function again but at the time when we are calling it in any JSX tag attribute like the onClick attribute in the above example. 

This is less common and less efficient because it creates a new instance of the arrow function every time when rendering and calling the event handler.

Conclusion

Proper binding of the event handlers in react is important so as to ensure that your code and functions work as expected and to ensure this, the correct context of this keyword is important.

In this blog, we discussed three methods with which we can bind event handlers with this in react. The first two methods are the most common and recommended while the third is less efficient. Each method has its advantages and you should choose according to your project’s requirements. Hope you got a fair idea about different methods of binding and why the binding of event handlers is important in React.