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Event Handling

The React docs for handling events show how an event handler can be attached to a React element. To type these event handlers you may use the SyntheticEvent<T> types like this:

1import {useState} from 'react';2import * as React from 'react';3
4function MyComponent(): React.Node {5  const [state, setState] = useState({count: 0});
                                                
6
7  const handleClick = (event: SyntheticEvent<HTMLButtonElement>) => {
                                            
                                                              
8    // To access your button instance use `event.currentTarget`.9    event.currentTarget as HTMLButtonElement;
                                            
10
11    setState(prevState => ({12      count: prevState.count + 1,13    }));14  };15
16  return (17    <div>18      <p>Count: {state.count}</p>19      <button onClick={handleClick}>Increment</button>20    </div>21  );22}
5:29-5:48: Cannot call hook [1] because React hooks can only be called within components or hooks. Under the current configuration, we only infer component-syntax components to be components and hook-syntax hooks to be hooks. (https://react.dev/reference/rules/rules-of-hooks) [react-rule-hook]
7:31-7:44: Cannot resolve name `SyntheticEvent`. [cannot-resolve-name]
7:46-7:62: Cannot resolve name `HTMLButtonElement`. [cannot-resolve-name]
9:28-9:44: Cannot resolve name `HTMLButtonElement`. [cannot-resolve-name]

There are also more specific synthetic event types like SyntheticKeyboardEvent<T>, SyntheticMouseEvent<T>, or SyntheticTouchEvent<T>. The SyntheticEvent<T> types all take a single type argument: the type of the HTML element the event handler was placed on.

If you don't want to add the type of your element instance you can also use SyntheticEvent with no type arguments like so: SyntheticEvent<>.

Note: To get the element instance, like HTMLButtonElement in the example above, it is a common mistake to use event.target instead of event.currentTarget. The reason you want to use event.currentTarget is that event.target may be the wrong element due to event propagation.

Note: React uses its own event system so it is important to use the SyntheticEvent types instead of the DOM types such as Event, KeyboardEvent, and MouseEvent.

The SyntheticEvent<T> types that React provides and the DOM events they are related to are: