30秒学会 React 片段 – ControlledInput

Renders an <input> element with internal state, that uses a callback function to pass its value to the parent component.

• Use object destructuring to set defaults for certain attributes of the <input> element.
• Use the React.setState() hook to create the value state variable and give it a value of equal to the defaultValue prop.
• Use the React.useEffect() hook with a second parameter set to the value state variable to call the callback function every time value is updated.
• Render an <input> element with the appropriate attributes and use the the onChange event to upda the value state variable.

代码实现

function ControlledInput({
  callback,
  type = 'text',
  disabled = false,
  readOnly = false,
  defaultValue,
  placeholder = ''
}) {
  const [value, setValue] = React.useState(defaultValue);

  React.useEffect(() => {
    callback(value);
  }, [value]);

  return (
    <input
      defaultValue={defaultValue}
      type={type}
      disabled={disabled}
      readOnly={readOnly}
      placeholder={placeholder}
      onChange={({ target: { value } }) => setValue(value)}
    />
  );
}

使用样例

ReactDOM.render(
  <ControlledInput
    type="text"
    placeholder="Insert some text here..."
    callback={val => console.log(val)}
  />,
  document.getElementById('root')
);