1var expanders = document.getElementsByClassName('expander');
 2for (var i = 0; i < expanders.length; i++) {
 3  (function() {
 4    var expander = expanders[i];
 5    var content = expander.children[0];
 6
 7    var button = document.createElement('button');
 8    button.appendChild(document.createTextNode('expand'));
 9    expander.appendChild(button);
10
11    content.style.height = expander.dataset.height || '12.5em';
12    button.onclick = function() {
13      content.style.height = 'auto';
14      button.remove();
15    }
16  })();
17}