text: function includeHTML() {
  	var z, i, elmnt, file, xhttp;
  	/* Loop through a collection of all HTML elements: */
  	z = document.getElementsByTagName('*');
  	for (i = 0; i < z.length; i++) {
  		elmnt = z[i];
  		/*search for elements with a certain atrribute:*/
  		file = elmnt.getAttribute('w3-include-html');
  		if (file) {
  			/* Make an HTTP request using the attribute value as the file name: */
  			xhttp = new XMLHttpRequest();
  			xhttp.onreadystatechange = function() {
  				if (this.readyState == 4) {
  					if (this.status == 200) {
  						elmnt.innerHTML = this.responseText;
  					}
  					if (this.status == 404) {
  						elmnt.innerHTML = 'Page not found.';
  					}
  					/* Remove the attribute, and call this function once more: */
  					elmnt.removeAttribute('w3-include-html');
  					includeHTML();
  				}
  			};
  			xhttp.open('GET', file, true);
  			xhttp.send();
  			/* Exit the function: */
  			return;
  		}
  	}
  }
  