Creating a DOM Node in JavaScript

To create a node in JavaScript, you can use the createElement method from the document object. Here is a succinct code snippet to accomplish this:

/**
 * Creates a new DOM node with the specified tag name.
 *
 * @param {string} tagName - The name of the tag for the new node.
 * @returns {Element} - The newly created DOM node.
 */
function createNode(tagName) {
  return document.createElement(tagName);
}

Usage example:

const div = createNode('div');
console.log(div); // <div></div>

In the example above, the createNode function is called with the argument 'div', which creates a new <div> element. The newly created node is then logged to the console.

Unit testing can be done using a testing framework like Jest. Here is an example of a unit test using Jest:

test('createNode creates a new node with the specified tag name', () => {
  const div = createNode('div');
  
  expect(div.tagName.toLowerCase()).toBe('div');
});

In the test above, we create a new div node using the createNode function and assert that its tag name is 'div'.