Function getValueForAttribute

docs/external/js/react-dom.development.js:1269–1287

* Get the value for a attribute on a node. Only used in DEV for SSR validation. * The third argument is used as a hint of what the expected value is. Some * attributes have multiple equivalent values.

(node, name, expected)

   */

  function getValueForAttribute(node, name, expected) {
    {
      if (!isAttributeNameSafe(name)) {
        return;
      }

      if (!node.hasAttribute(name)) {
        return expected === undefined ? undefined : null;
      }

      var value = node.getAttribute(name);

      if (value === '' + expected) {
        return expected;
      }

      return value;
    }
  }
  /**
   * Sets the value for a property on a node.
   *