30秒学会 React 片段 – Select

Renders a <select> element that uses a callback function to pass its value to the parent component.

• Use object destructuring to set defaults for certain attributes of the <select> element.
• Render a <select> element with the appropriate attributes and use the callback function in the onChange event to pass the value of the textarea to the parent.
• Use destructuring on the values array to pass an array of value and text elements and the selected attribute to define the initial value of the <select> element.

代码实现

function Select({ values, callback, disabled = false, readonly = false, 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>
  );
}

使用样例

let choices = [
  ['grapefruit', 'Grapefruit'],
  ['lime', 'Lime'],
  ['coconut', 'Coconut'],
  ['mango', 'Mango']
];
ReactDOM.render(
  <Select values={choices} selected="lime" callback={val => console.log(val)} />,
  document.getElementById('root')
);