Answers for "react usestate update object"

Javascript

update object in react hooks

- Through Input

        const [state, setState] = useState({ fName: "", lName: "" });
        const handleChange = e => {
            const { name, value } = e.target;
            setState(prevState => ({
                ...prevState,
                [name]: value
            }));
        };

        <input
            value={state.fName}
            type="text"
            onChange={handleChange}
            name="fName"
        />
        <input
            value={state.lName}
            type="text"
            onChange={handleChange}
            name="lName"
        />
   ***************************

 - Through onSubmit or button click
    
        setState(prevState => ({
            ...prevState,
            fName: 'your updated value here'
         }));

Posted by: Guest on January-02-2021

Source

prevstate in usestate

const [prevState, setState] = React.useState([]);

setState(prevState => [...prevState, 'somedata'] );

Posted by: Guest on June-09-2020

react setstate in hooks to array of objects value

// sample datas structure
/* const datas = [
    {
      id:   1,
      name: 'john',
      gender: 'm'
    }
    {
      id:   2,
      name: 'mary',
      gender: 'f'
    }
] */ // make sure to set the default value in the useState call (I already fixed it)

const [datas, setDatas] = useState([
    {
      id:   1,
      name: 'john',
      gender: 'm'
    }
    {
      id:   2,
      name: 'mary',
      gender: 'f'
    }
]);

const updateFieldChanged = index => e => {

    console.log('index: ' + index);
    console.log('property name: '+ e.target.name);
    let newArr = [...datas]; // copying the old datas array
    newArr[index] = e.target.value; // replace e.target.value with whatever you want to change it to

    setDatas(newArr); // ??
}

return (
    <React.Fragment>
        { datas.map( (data, index) => {
              <li key={data.name}>
                <input type="text" name="name" value={data.name} onChange={updateFieldChanged(index)}  />
              </li>
          })
        }
    </React.Fragment>
)

Posted by: Guest on March-02-2021

Source

updating one state of an object of states react useState

function LoginForm() {
  const [form, setState] = useState({
    username: '',
    password: ''
  });

  const printValues = e => {
    e.preventDefault();
    console.log(form.username, form.password);
  };

  const updateField = e => {
    setState({
      ...form,
      [e.target.name]: e.target.value
    });
  };

  return (
    <form onSubmit={printValues}>
      <label>
        Username:
        <input
          value={form.username}
          name="username"
          onChange={updateField}
        />
      </label>
      <br />
      <label>
        Password:
        <input
          value={form.password}
          name="password"
          type="password"
          onChange={updateField}
        />
      </label>
      <br />
      <button>Submit</button>
    </form>
  );
}

Posted by: Guest on July-22-2021

Source

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