¿Cómo cambio el valor de mi estado?

How do I change my state value?

To update our state, we use this. setState() and pass in an object. This object will get merged with the current state. When the state has been updated, our component re-renders automatically.

With React class components you have the componentDidUpdate method which receives previous props and state as arguments or you can update an instance variable (this. previous = value) and reference it later to get the previous value.

6. What does the “webpack” command do? Runs react local development server.

Here are other ways to utilize previous state: import React from ‘react’; class DogToggle extends React. Component { constructor() { super(); // set initial state this. state = { isGoodDog: true }; } // when handleClick is called, setState will update the state so that isGoodDog is reversed handleClick = () => { this.

If you use the useMemo hook on top of your component and have it dependent on all your props, it runs before everything everytime props change. useEffect is triggered after the updated render and since dependent on all props it triggers after a rerender depending on all props. setCount will trigger a re-render.

Here is the code that shows accessing a state value ( clickCounts) right after setting it synchronously. And let’s see the logical error. console.log doesn’t have access to updated state value even though the call is made after setState. As setState is an operation, you can just wait till the value is set by React.

setState () does not immediately mutate this.state but creates a pending state transition. Accessing this.state after calling this method can potentially return the existing value. There is no guarantee of synchronous operation of calls to setState and calls may be batched for performance gains.

But the handleCounter and handleIsValid methods are now functional and start by grabbing the current state and then, depending on that state, changing it to the next one. This is the correct way of changing the state of variables that depend on the previous state.

The difference is that useState in this example is called with a function that returns the initial state (rather than simply passing the initial state) and setCount (dispatch) is called with a function that accepts the previous state value and returns the new one.