2024 05 17 title incompatible types issue with typescript touch event handler - bizkite-co/handterm GitHub Wiki


original file name: Codeium Chat - AXiYRmnsw5SSSxMDmrokSNYWBjBadMmm.md summary: The user is facing an issue with TypeScript regarding incompatible types for a Touch event handler. The onTouchStart prop in the Output component expects a function with the type TouchEventHandler<HTMLDivElement>, but the handleTouchStart function being passed does not match this type. To resolve this, the user needs to update the handleTouchStart function to accept the correct event type, TouchEvent<HTMLDivElement>. Additionally, the user encountered an error message stating that TouchEvent is not a generic type in TypeScript, but should be using the React.TouchEventHandler<HTMLDivElement> type for handling touch events in React. date: 2024-05-17T18:17

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User at 6:17 pm, May 17, 2024

Explain problem: Type '(event: TouchEventHandler<HTMLDivElement>) => void' is not assignable to type 'TouchEventHandler<HTMLDivElement>'. Types of parameters 'event' and 'event' are incompatible. Type 'TouchEvent<HTMLDivElement>' is not assignable to type 'TouchEventHandler<HTMLDivElement>'. Type 'TouchEvent<HTMLDivElement>' provides no match for the signature '(event: TouchEvent<HTMLDivElement>): void'.


Codeium at 6:17 pm, May 17, 2024

The issue you're facing is that the onTouchStart prop in your Output component is expecting a function with the type TouchEventHandler<HTMLDivElement>, but the function handleTouchStart you are passing does not match this type.

To fix this, you need to ensure that the handleTouchStart function has the correct type signature. The TouchEventHandler<HTMLDivElement> type should take an argument of type TouchEvent<HTMLDivElement>.

You can update your handleTouchStart function to accept the correct event type like this:

private handleTouchStart: TouchEventHandler<HTMLDivElement> = (event: TouchEvent<HTMLDivElement>) => {
  setTimeout(() => {
    // this.terminalElement.focus();
  }, 500)
  if (event.touches.length === 2) {
    console.log('handleTouchStart', event);
    this.lastTouchDistance = this.getDistanceBetweenTouches(event.touches.slice(0, 2));
  }
}

By specifying the function type directly when defining handleTouchStart, you ensure that it matches the expected type for the onTouchStart prop in the Output component.


User at 6:21 pm, May 17, 2024

That tell me:

Type 'TouchEvent' is not generic.ts(2315)
⚠ Error (TS2315)  | 
Type  TouchEvent 
 is not generic.
Codeium: Explain Problem
interface TouchEvent
An event sent when the state of contacts with a touch-sensitive surface changes. This surface can be a touch screen or trackpad, for example. The event can describe one or more points of contact with the screen and includes support for detecting movement, addition and removal of contact points, and so forth.

Codeium at 6:21 pm, May 17, 2024

I apologize for the confusion. The error message you're seeing indicates that TouchEvent is not a generic type in TypeScript, which means it cannot take type parameters like TouchEvent<HTMLDivElement>.

The TouchEventHandler<T> type, however, is a generic type that expects the event target type as its generic parameter. So, the correct way to type your handleTouchStart method is to ensure it matches the TouchEventHandler type signature.

Here is how you should define your handleTouchStart method:

private handleTouchStart: React.TouchEventHandler<HTMLDivElement> = (event: React.TouchEvent<HTMLDivElement>) => {
  // Your implementation here
};

Ensure that handleTouchStart is a method of your component class and that it correctly handles the event according to the React type definitions for touch events. If there are still issues, you may need to check that your TypeScript version aligns with your React version and that your type definitions are up to date.

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