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VisualizaçõesReact, passing state from a Child component to the Parent
I'm just learning React and ran into a problem. I'm making a bunch of counter components that look like this :
The problem is that I have defined the state in each of these counters which is 3 of them and I'd like to pass the value (number) into the parent so I can add it up and display the total count.
Here is my child counter component:
import React, { useState } from "react";
const Counter = () => {
const [count, setcount] = useState(0)
const handleIncrement=()=>{
setcount(count+1);
}
const handleDecrement=()=>{
setcount(count+-1);
}
return (
<div>
<button onClick={()=>{handleIncrement()}}>+</button>
<span>{count}</span>
<button onClick={()=>{handleDecrement()}}>-</button>
</div>
);
};
export default Counter;
And here is the parent which I want to pass my values to so I can add them up and show the total :
import React from 'react'
import Counter from './Counter'
const Counters = () => {
return (
<>
<h3>totalcount:</h3>
<Counter/>
<Counter/>
<Counter/>
</>
)
}
export default Counters
What I tried was to make multiple states but I can't get a good way to make this. I know there's an easy answer for this and I'm making it too complicated. If you guys have other optimization for my code please share.
1 Respostas
Responde à pergunta0
In React state goes top to bottom. A nested component can update the state of a parent if a function defined in the parent has been passed to it as props. Which means, what you wanna do is not possible as your code is set up. A way to achieve what you are looking for is :
import React, { useState } from "react";
const Counter = ({count, setCount}) => {
const handleIncrement=()=>{
setCount(count+1);
}
const handleDecrement=()=>{
setCount(count+-1);
}
return (
<div>
<button onClick={()=>{handleIncrement()}}>+</button>
<span>{count}</span>
<button onClick={()=>{handleDecrement()}}>-</button>
</div>
);
};
export default Counter;
import React, { useState } from 'react'
import Counter from './Counter'
const Counters = () => {
const [countOne, setCountOne] = useState(0)
const [countTwo, setCountTwo] = useState(0)
const [countThree, setCountThree] = useState(0)
return (
<>
<h3>totalcount: {countOne + countTwo countThree} </h3>
<Counter count = {countOne} setCount = {setCountOne} />
<Counter count = {countTwo} setCount = {setCount} />
<Counter count = {countThree} setCount = {setCountThree} />
</>
)
}
export default Counters