Javascript template engine

template.js

function template(html, data){
  //process html template
  html = html.replace(/>/g, ">")
            .replace(/&lt;/g, "<")
            .replace(/[\r\t\n]\s+/g, '')
            .trim();
  
  var re = /<%([^>]+)?%>/g, 
      reExp = /(^( )?(if|for|else|switch|case|break|{|}|var|let|const))(.*)?/g, 
      code = 'var r=[];\n', 
      cursor = 0, 
      match;
  var add = function(line, js) {
      js? (code += line.match(reExp) ? line + '\n' : 'r.push(' + line + ');\n') :
          (code += line != '' ? 'r.push("' + line.replace(/"/g, '\\"') + '");\n' : '');
      return add;
  }
  while(match = re.exec(html)) {
      add(html.slice(cursor, match.index))(match[1], true);
      cursor = match.index + match[0].length;
  }
  add(html.slice(cursor));
  code += 'return r.join("");';
  return new Function(code).apply(data);
}