initTextarea() — react Function Reference

Source Code

packages/react-dom-bindings/src/client/ReactDOMTextarea.js lines 93–148

export function initTextarea(
  element: Element,
  value: ?string,
  defaultValue: ?string,
  children: ?string,
) {
  const node: HTMLTextAreaElement = (element: any);

  let initialValue = value;

  // Only bother fetching default value if we're going to use it
  if (initialValue == null) {
    if (children != null) {
      if (!disableTextareaChildren) {
        if (defaultValue != null) {
          throw new Error(
            'If you supply `defaultValue` on a <textarea>, do not pass children.',
          );
        }

        if (isArray(children)) {
          if (children.length > 1) {
            throw new Error('<textarea> can only have at most one child.');
          }

          children = children[0];
        }

        defaultValue = children;
      }
    }
    if (defaultValue == null) {
      defaultValue = '';
    }
    initialValue = defaultValue;
  }

  const stringValue = getToStringValue(initialValue);
  node.defaultValue = (stringValue: any); // This will be toString:ed.

  // This is in postMount because we need access to the DOM node, which is not
  // available until after the component has mounted.
  const textContent = node.textContent;

  // Only set node.value if textContent is equal to the expected
  // initial value. In IE10/IE11 there is a bug where the placeholder attribute
  // will populate textContent as well.
  // https://developer.microsoft.com/microsoft-edge/platform/issues/101525/
  if (textContent === stringValue) {
    if (textContent !== '' && textContent !== null) {
      node.value = textContent;
    }
  }

  track((element: any));
}