devinrhode2/extends-HTMLElement.ts

## extends-HTMLElement.ts
type asdf = HTMLElement;

const validateElement = <
  // eslint-disable-next-line @typescript-eslint/ban-types
  TInstanceType extends Element,
>(
  node: Element | null,
  {
    nodeNickname,
    tagName,
    instanceType,
  }: {
    nodeNickname: string;
    tagName: 'head' | 'body';
    instanceType: TInstanceType;
  },
): node is TInstanceType => {
  if (!node) {
    throw new Error(`No ${nodeNickname} in html`);
  }
  if (node.tagName.toLowerCase() !== tagName.toLowerCase()) {
    throw new Error(
      `${nodeNickname} is not a <${tagName}> tag.`,
    );
  }
  if (!(node instanceof instanceType)) {
    throw new Error(
      `node is not an instanceof ${instanceType.name}`,
    );
  }

  return true;
};

export const getPrimaryHtmlNodes = (
  html: string,
): {
  headNode: HTMLHeadElement;
  bodyNode: HTMLBodyElement;
} => {
  const fullDoc = document.createElement('html');

  fullDoc.innerHTML = html;

  // TODO: use something better than `firstElementChild` to find `head`?
  const headNode = fullDoc.firstElementChild;

  if (
    validateElement(headNode, {
      nodeNickname: 'firstElementChild',
      tagName: 'head',
      instanceType: HTMLHeadElement,
    })
  ) {
  }

  if (!headNode) {
    throw new Error('No firstElementChild in html');
  }
  if (
    // TODO: use something better than `firstElementChild` to find `head`?
    headNode.tagName.toLowerCase() !== 'head'
  ) {
    throw new Error(
      'firstElementChild is not a <head> tag. Maybe this is an unhandled browser bug?',
    );
  }
  if (!(headNode instanceof HTMLHeadElement)) {
    throw new Error(
      'headNode is not an instanceof HTMLHeadElement',
    );
  }

  const bodyNode = fullDoc.lastElementChild;
  if (!bodyNode) {
    throw new Error('No lastElementChild in html');
  }
  if (
    // TODO: use something better than `lastElementChild` to find `body`
    bodyNode.tagName.toLowerCase() !== 'body'
  ) {
    throw new Error(
      'lastElementChild is not a <body> tag. Maybe this is an unhandled browser bug?',
    );
  }
  if (!(bodyNode instanceof HTMLBodyElement)) {
    throw new Error(
      'bodyNode is not an instanceof HTMLBodyElement',
    );
  }

  return { headNode, bodyNode };
};
	type asdf = HTMLElement;

	const validateElement = <
	// eslint-disable-next-line @typescript-eslint/ban-types
	TInstanceType extends Element,
	>(
	node: Element \| null,
	{
	nodeNickname,
	tagName,
	instanceType,
	}: {
	nodeNickname: string;
	tagName: 'head' \| 'body';
	instanceType: TInstanceType;
	},
	): node is TInstanceType => {
	if (!node) {
	throw new Error(`No ${nodeNickname} in html`);
	}
	if (node.tagName.toLowerCase() !== tagName.toLowerCase()) {
	throw new Error(
	`${nodeNickname} is not a <${tagName}> tag.`,
	);
	}
	if (!(node instanceof instanceType)) {
	throw new Error(
	`node is not an instanceof ${instanceType.name}`,
	);
	}

	return true;
	};

	export const getPrimaryHtmlNodes = (
	html: string,
	): {
	headNode: HTMLHeadElement;
	bodyNode: HTMLBodyElement;
	} => {
	const fullDoc = document.createElement('html');

	fullDoc.innerHTML = html;

	// TODO: use something better than `firstElementChild` to find `head`?
	const headNode = fullDoc.firstElementChild;

	if (
	validateElement(headNode, {
	nodeNickname: 'firstElementChild',
	tagName: 'head',
	instanceType: HTMLHeadElement,
	})
	) {
	}

	if (!headNode) {
	throw new Error('No firstElementChild in html');
	}
	if (
	// TODO: use something better than `firstElementChild` to find `head`?
	headNode.tagName.toLowerCase() !== 'head'
	) {
	throw new Error(
	'firstElementChild is not a <head> tag. Maybe this is an unhandled browser bug?',
	);
	}
	if (!(headNode instanceof HTMLHeadElement)) {
	throw new Error(
	'headNode is not an instanceof HTMLHeadElement',
	);
	}

	const bodyNode = fullDoc.lastElementChild;
	if (!bodyNode) {
	throw new Error('No lastElementChild in html');
	}
	if (
	// TODO: use something better than `lastElementChild` to find `body`
	bodyNode.tagName.toLowerCase() !== 'body'
	) {
	throw new Error(
	'lastElementChild is not a <body> tag. Maybe this is an unhandled browser bug?',
	);
	}
	if (!(bodyNode instanceof HTMLBodyElement)) {
	throw new Error(
	'bodyNode is not an instanceof HTMLBodyElement',
	);
	}

	return { headNode, bodyNode };
	};