The built-in browser <select> component lets you render a select box with options.

<select>
  <option value="someOption">Some option</option>
  <option value="otherOption">Other option</option>
</select>

Reference

<select>

To display a select box, render the built-in browser <select> component.

<select>
  <option value="someOption">Some option</option>
  <option value="otherOption">Other option</option>
</select>

See more examples below.

Props

<select> supports all common element props.

You can make a select box controlled by passing a value prop:

  • value: A string (or an array of strings for multiple={true}). Controls which option is selected. Every value string match the value of some <option> nested inside the <select>.

When you pass value, you must also pass an onChange handler that updates the passed value.

If your <select> is uncontrolled, you may pass the defaultValue prop instead:

These <select> props are relevant both for uncontrolled and controlled select boxes:

  • autoComplete: A string. Specifies one of the possible autocomplete behaviors.
  • autoFocus: A boolean. If true, React will focus the element on mount.
  • children: <select> accepts <option>, <optgroup>, and <datalist> components as children. You can also pass your own components as long as they eventually render one of the allowed components. If you pass your own components that eventually render <option> tags, each <option> you render must have a value.
  • disabled: A boolean. If true, the select box will not be interactive and will appear dimmed.
  • form: A string. Specifies the id of the <form> this select box belongs to. If omitted, it’s the closest parent form.
  • multiple: A boolean. If true, the browser allows multiple selection.
  • name: A string. Specifies the name for this select box that’s submitted with the form.
  • onChange: An Event handler function. Required for controlled select boxes. Fires immediately when the user picks a different option. Behaves like the browser input event.
  • onChangeCapture: A version of onChange that fires in the capture phase.
  • onInput: An Event handler function. Fires immediately when the value is changed by the user. For historical reasons, in React it is idiomatic to use onChange instead which works similarly.
  • onInputCapture: A version of onInput that fires in the capture phase.
  • onInvalid: An Event handler function. Fires if an input fails validation on form submit. Unlike the built-in invalid event, the React onInvalid event bubbles.
  • onInvalidCapture: A version of onInvalid that fires in the capture phase.
  • required: A boolean. If true, the value must be provided for the form to submit.
  • size: A number. For multiple={true} selects, specifies the preferred number of initially visible items.

Caveats

  • Unlike in HTML, passing a selected attribute to <option> is not supported. Instead, use <select defaultValue> for uncontrolled select boxes and <select value> for controlled select boxes.
  • If a select box receives a value prop, it will be treated as controlled.
  • A select box can’t be both controlled and uncontrolled at the same time.
  • A select box cannot switch between being controlled or uncontrolled over its lifetime.
  • Every controlled select box needs an onChange event handler that synchronously updates its backing value.

Usage

Displaying a select box with options

Render a <select> with a list of <option> components inside to display a select box. Give each <option> a value representing the data to be submitted with the form.

export default function FruitPicker() {
  return (
    <label>
      Pick a fruit:
      <select name="selectedFruit">
        <option value="apple">Apple</option>
        <option value="banana">Banana</option>
        <option value="orange">Orange</option>
      </select>
    </label>
  );
}

Providing a label for a select box

Typically, you will place every <select> inside a <label> tag. This tells the browser that this label is associated with that select box. When the user clicks the label, the browser will automatically focus the select box. It’s also essential for accessibility: a screen reader will announce the label caption when the user focuses the select box.

If you can’t nest <select> into a <label>, associate them by passing the same ID to <select id> and <label htmlFor>. To avoid conflicts between multiple instances of one component, generate such an ID with useId.

import { useId } from 'react';

export default function Form() {
  const vegetableSelectId = useId();
  return (
    <>
      <label>
        Pick a fruit:
        <select name="selectedFruit">
          <option value="apple">Apple</option>
          <option value="banana">Banana</option>
          <option value="orange">Orange</option>
        </select>
      </label>
      <hr />
      <label htmlFor={vegetableSelectId}>
        Pick a vegetable:
      </label>
      <select id={vegetableSelectId} name="selectedVegetable">
        <option value="cucumber">Cucumber</option>
        <option value="corn">Corn</option>
        <option value="tomato">Tomato</option>
      </select>
    </>
  );
}

Providing an initially selected option

By default, the browser will select the first <option> in the list. To select a different option by default, pass that <option>’s value as the defaultValue to the <select> element.

export default function FruitPicker() {
  return (
    <label>
      Pick a fruit:
      <select name="selectedFruit" defaultValue="orange">
        <option value="apple">Apple</option>
        <option value="banana">Banana</option>
        <option value="orange">Orange</option>
      </select>
    </label>
  );
}

陷阱

Unlike in HTML, passing a selected attribute to an individual <option> is not supported.

Enabling multiple selection

Pass multiple={true} to the <select> to let the user select multiple options. In that case, if you also specify defaultValue to choose the initially selected options, it must be an array.

export default function FruitPicker() {
  return (
    <label>
      Pick some fruits:
      <select
        name="selectedFruit"
        defaultValue={['orange', 'banana']}
        multiple={true}
      >
        <option value="apple">Apple</option>
        <option value="banana">Banana</option>
        <option value="orange">Orange</option>
      </select>
    </label>
  );
}

Reading the select box value when submitting a form

Add a <form> around your select box with a <button type="submit"> inside. It will call your <form onSubmit> event handler. By default, the browser will send the form data to the current URL and refresh the page. You can override that behavior by calling e.preventDefault(). Read the form data with new FormData(e.target).

export default function EditPost() {
  function handleSubmit(e) {
    // Prevent the browser from reloading the page
    e.preventDefault();
    // Read the form data
    const form = e.target;
    const formData = new FormData(form);
    // You can pass formData as a fetch body directly:
    fetch('/some-api', { method: form.method, body: formData });
    // You can generate a URL out of it, as the browser does by default:
    console.log(new URLSearchParams(formData).toString());
    // You can work with it as a plain object.
    const formJson = Object.fromEntries(formData.entries());
    console.log(formJson); // (!) This doesn't include multiple select values
    // Or you can get an array of name-value pairs.
    console.log([...formData.entries()]);
  }

  return (
    <form method="post" onSubmit={handleSubmit}>
      <label>
        Pick your favorite fruit:
        <select name="selectedFruit" defaultValue="orange">
          <option value="apple">Apple</option>
          <option value="banana">Banana</option>
          <option value="orange">Orange</option>
        </select>
      </label>
      <label>
        Pick all your favorite vegetables:
        <select
          name="selectedVegetables"
          multiple={true}
          defaultValue={['corn', 'tomato']}
        >
          <option value="cucumber">Cucumber</option>
          <option value="corn">Corn</option>
          <option value="tomato">Tomato</option>
        </select>
      </label>
      <hr />
      <button type="reset">Reset</button>
      <button type="submit">Submit</button>
    </form>
  );
}

注意

Give a name to your <select>, for example <select name="selectedFruit" />. The name you specified will be used as a key in the form data, for example { selectedFruit: "orange" }.

If you use <select multiple={true}>, the FormData you’ll read from the form will include each selected value as a separate name-value pair. Look closely at the console logs in the example above.

陷阱

By default, any <button> inside a <form> will submit it. This can be surprising! If you have your own custom Button React component, consider returning <button type="button"> instead of <button>. Then, to be explicit, use <button type="submit"> for buttons that are supposed to submit the form.

Controlling a select box with a state variable

A select box like <select /> is uncontrolled. Even if you pass an initially selected value like <select defaultValue="orange" />, your JSX only specifies the initial value, not the value right now.

To render a controlled select box, pass the value prop to it. React will force the select box to always have the value you passed. Typically, you will control a select box by declaring a state variable:

function FruitPicker() {
  const [selectedFruit, setSelectedFruit] = useState('orange'); // Declare a state variable...
  // ...
  return (
    <select
      value={selectedFruit} // ...force the select's value to match the state variable...
      onChange={e => setSelectedFruit(e.target.value)} // ... and update the state variable on any change!
    >
      <option value="apple">Apple</option>
      <option value="banana">Banana</option>
      <option value="orange">Orange</option>
    </select>
  );
}

This is useful if you want to re-render some part of the UI in response to every selection.

import { useState } from 'react';

export default function FruitPicker() {
  const [selectedFruit, setSelectedFruit] = useState('orange');
  const [selectedVegs, setSelectedVegs] = useState(['corn', 'tomato']);
  return (
    <>
      <label>
        Pick a fruit:
        <select
          value={selectedFruit}
          onChange={e => setSelectedFruit(e.target.value)}
        >
          <option value="apple">Apple</option>
          <option value="banana">Banana</option>
          <option value="orange">Orange</option>
        </select>
      </label>
      <hr />
      <label>
        Pick all your favorite vegetables:
        <select
          multiple={true}
          value={selectedVegs}
          onChange={e => {
            const options = [...e.target.selectedOptions];
            const values = options.map(option => option.value);
            setSelectedVegs(values);
          }}
        >
          <option value="cucumber">Cucumber</option>
          <option value="corn">Corn</option>
          <option value="tomato">Tomato</option>
        </select>
      </label>
      <hr />
      <p>Your favorite fruit: {selectedFruit}</p>
      <p>Your favorite vegetables: {selectedVegs.join(', ')}</p>
    </>
  );
}

陷阱

If you pass value without onChange, it will be impossible to select an option. When you control a select box by passing some value to it, you force it to always have the value you passed. So if you pass a state variable as a value but forget to update that state variable synchronously during the onChange event handler, React will revert the select box after every keystroke back to the value that you specified.

Unlike in HTML, passing a selected attribute to an individual <option> is not supported.

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