function updateText (txt) {
      const items = txt.split(';');
      selElems.forEach((elem) => {
        if (elem && elem.getAttribute('class').includes('placemark')) {
          const elements = elem.children;
          Array.prototype.forEach.call(elements, function(i, _){
            const [ , , type, n ] = i.id.split('_');
            if (type === 'txt') {
              txt.textContent = items[n];
            }
          });
        }
      });
    }
Called when text is changed.
@param {string} txt
@returns {void}