How can I set the value of a select input in React?

Adding selected to an option

A very common way of setting a <select> input's value is by adding a selected attribute to one of its <option> elements. For example:

const Select = ({ values, callback, selected }) => {
  return (
    <select
      disabled={disabled}
      readOnly={readonly}
      onChange={({ target: { value } }) => callback(value)}
    >
      {values.map(([value, text]) => (
        <option selected={selected === value} value={value}>
          {text}
        </option>
      ))}
    </select>
  );
}

While this approach closely resembles HTML and feels intuitive, there is an easier way to do the same thing. React provides us with a shared API between <input type="text">, <textarea> and <select> where we can use value or defaultValue (depending if the input is controlled or not) to set the field's value.

Using this API, we minimize the effort of checking for the selected value, as well as making the code easier to read and update as necessary. Here's an example:

const Select = ({ values, callback, selected }) => {
  return (
    <select
      disabled={disabled}
      readOnly={readonly}
      defaultValue={selected}
      onChange={({ target: { value } }) => callback(value)}
    >
      {values.map(([value, text]) => (
        <option value={value}>
          {text}
        </option>
      ))}
    </select>
  );
}

Note that the above implementation uses defaultValue, therefore it implies that the component is uncontrolled. You can convert this Select component into a controlled component by using value instead of defaultValue.

Making a reusable component

Putting everything we've seen together, we can create an uncontrolled <select> component that uses a callback function to pass its value to the parent component.

To make its API as usable as possible, we'll use the selectedValue prop as the defaultValue of the <select> element to set its initial value. We'll also use the onChange event to fire the onValueChange callback and send the new value to the parent.

Finally, we'll use Array.prototype.map() on the values array to create an <option> element for each passed value. Each item in values must be a 2-element array, where the first element is the value of the item and the second one is the displayed text for it.

const Select = ({ values, onValueChange, selectedValue, ...rest }) => {
  return (
    <select
      defaultValue={selectedValue}
      onChange={({ target: { value } }) => onValueChange(value)}
      {...rest}
    >
      {values.map(([value, text]) => (
        <option key={value} value={value}>
          {text}
        </option>
      ))}
    </select>
  );
};

const choices = [
  ['grapefruit', 'Grapefruit'],
  ['lime', 'Lime'],
  ['coconut', 'Coconut'],
  ['mango', 'Mango'],
];

ReactDOM.createRoot(document.getElementById('root')).render(
  <Select
    values={choices}
    selectedValue="lime"
    onValueChange={val => console.log(val)}
  />
);