getValueForAttributeOnCustomComponent() — react Function Reference

Source Code

packages/react-dom-bindings/src/client/DOMPropertyOperations.js lines 56–96

export function getValueForAttributeOnCustomComponent(
  node: Element,
  name: string,
  expected: mixed,
): mixed {
  if (__DEV__) {
    if (!isAttributeNameSafe(name)) {
      return;
    }
    if (!node.hasAttribute(name)) {
      // shouldRemoveAttribute
      switch (typeof expected) {
        case 'symbol':
        case 'object':
          // Symbols and objects are ignored when they're emitted so
          // it would be expected that they end up not having an attribute.
          return expected;
        case 'function':
          return expected;
        case 'boolean':
          if (expected === false) {
            return expected;
          }
      }
      return expected === undefined ? undefined : null;
    }
    const value = node.getAttribute(name);

    if (value === '' && expected === true) {
      return true;
    }

    if (__DEV__) {
      checkAttributeStringCoercion(expected, name);
    }
    if (value === '' + (expected: any)) {
      return expected;
    }
    return value;
  }
}