Question 244346 in Javascript Question posted in
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Javascript – Accessing array with JSON in React

I have a structure as follows:

  const [res, setRes] = useState({
    question: "",
    option: [, , , ,],
    answer: 0,
  });

I want to update the option array value with corresponding indices.

Example
I should be able to set option[3]:2

  const handleOption = (e) => {
    setRes((prev) => ({
      ...prev,
      option[e.target.id]:e.target.value,
    }));
  };

The above snippet gives error at options[e.

How to solve this?

Tags:

2

Answers


  1. 0

    To update a specific element in the option array in your state, you can create a new array.
    Here is one of the ways.

    const handleOption = (e) => {
  const { id, value } = e.target;
  setRes((prev) => {
    const updatedOption = [...prev.option]; // Create a copy of the option array
    updatedOption[id] = value; // Update the value at the specified index
    return { ...prev, option: updatedOption }; // Return the updated state
  });
};
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  2. 0

    Create a copy of your array using the previous value, update your desired index and return a new object to your state.

    const handleOption = e => {
  setRes(prev => {
    const newOptions = [...prev.options];
    newOptions[e.target.id] = e.target.value;

    return {
      ...prev,
      options: newOptions
    };
  });
};
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