how to add value to array of objects to a particular Index in React

Question

I want add data to array of object on button click, if index value not present create new object and add data

const [sampleArray, setSampleArray] = useState([{fruit:'', Vegetable:''}])

const addData=(index, value)=>
{
    setSampleArray()
}


on first click :  index = 1 & fruit = 'orange'
on second click :  index = 1 & vegetable = 'brinjal'
on third click :  index = 2 & fruit = 'Banana'
on fourth click :  index = 2 & fruit = 'cabbage'

<button onClick={addData}> submit </button>

result should be like this:

[{fruit:'orange', Vegetable:'brinjal'}, {fruit:'Banana', Vegetable:'cabbage'}]

Please share what have you tried and what error did you receive. Your addData method looks incomplete. — Vineet Desai
– Vineet Desai, Commented Jan 6, 2022 at 7:21
What is the type of 'value', how does addData know if 'value' is a fruit or a vegetable? — DannyMoshe
– DannyMoshe, Commented Jan 6, 2022 at 12:07

pitamer · Accepted Answer · 2022-01-07 00:32:10Z

1

Here is an example solution:

const addData = (index, value) => {
  const updatedArray = [...sampleArray];

  if (!updatedArray[index]) {
    // Add your data however you want
    updatedArray.push({})
  } else {
    // Change your data however you want
    updatedArray[index].fruit = value;
  }

  setSampleArray(updatedArray);
}

edited Jan 7, 2022 at 0:32

pitamer

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answered Jan 6, 2022 at 8:15

FlushBG

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1 Comment

FlushBG Over a year ago

For some reason I can't view the suggested edit, and not even who suggested it. So can you please type your suggestion as a comment under here?

MWO · Accepted Answer · 2022-01-06 13:11:29Z

You can introduce a clicks counter state variable to track the number of clicks. And the use the useEffect hook to check which index you are at. Then set your sampleArray fruit or Vegetable if it has not been set yet. If you still have more data for the next index, add a new empty object before writing the fruit. Thus you are not only limited to a fixed number of data.

function App() {
  const [sampleArray, setSampleArray] = React.useState([{ fruit: "", Vegetable: "" }]);

  const data = [{fruit:'orange', Vegetable:'brinjal'}, {fruit:'Banana', Vegetable:'cabbage'}, {fruit:'Apple', Vegetable:'nuts'}];

  const [clicks, setclicks] = React.useState(0);


  React.useEffect(()=>{
    if(!clicks) return;
    const index = Math.floor(clicks/2+0.5);
    let arr = sampleArray;
    if(clicks & 1){ //odd
      if(!arr[index-1] && data[index-1]) arr.push({ fruit: "", Vegetable: "" })
      if(!data[index-1]) return;
      arr[sampleArray.length -1].fruit = data[index-1].fruit;
      addData(index, arr)
    }else{ //even
      if(!data[index-1]) return;
      arr[sampleArray.length -1].Vegetable = data[index-1].Vegetable;
      addData(index, arr)
    }

  },[clicks])

  const addData = (index, value) =>{
    setSampleArray([...value]);
  }


  return (
    <div className="App">
      <button onClick={()=>setclicks(clicks+1)}> submit </button>
      <div>
        {JSON.stringify(sampleArray)}
      </div>
      <div>
        clicks: {clicks}
      </div>
    </div>
  );
}

ReactDOM.render( < App / > , document.getElementById("root"));

<script crossorigin src="https://unpkg.com/react@17/umd/react.development.js"></script>
<script crossorigin src="https://unpkg.com/react-dom@17/umd/react-dom.development.js"></script>
<div id="root"></div>

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