useState 钩子在 React Native 的 TextInput 中的 onKeyPress 处理程序中不起作用

Question

I'm using useState to keep the value of an input, and I need make some stuff when the taps a specific key, so I'm try to use onKeyPress , but the method used to update the state is not working, any help aprecciated :)

Here how the code looks like:

...
function handleKeyPress(event) {
  // This code looks like is not running, why?
  setMessageInput('asdasdasdasd')
}
...
<TextInput onKeyPress={handleKeyPress} />
...

Answer 1

It looks like you need to bind the function to the onKeyPress event handler. You can easily accomplish this by using an arrow function .

function handleKeyPress(event) {
  setMessageInput('asdasdasdasd')
}
...
<TextInput onKeyPress={(e) => handleKeyPress(e)} />

Answer 2

The problem with yours is a javscript statement , where functions in javascript needs explicit binding of this in class components and in functional components you can achieve the same by using fat arrow functions.

So try replacing the code with the below

const handleKeyPress = (event) => {
  setMessageInput('asdasdasdasd')
}

... 

<TextInput onKeyPress={(e) => handleKeyPress(e)} />

Hope it helps. feel free for doubts

Answer 3

我解决了这个问题，这是另一个处理程序异步执行的问题