npm install xmlbuilder

var builder = require('xmlbuilder').builder();

builder.begin()
  .ele('root')
    .ele('xmlbuilder')
      .att('for', 'node-js')
      .att('awesome', 'CoffeeScript')
      .ele('repo')
        .att('type', 'git')
        .txt('git://github.com/oozcitak/xmlbuilder-js.git') 
      .up()
    .up()
  .up()
  .ele('test')
    .txt('complete');

console.log(builder.toString({ pretty: true });

<root>
  <xmlbuilder for="node-js" awesome="CoffeeScript">
    <repo type="git">git://github.com/oozcitak/xmlbuilder-js.git</repo>
  </xmlbuilder>
  <test>complete</test>
</root>

var root = builder.begin().ele('squares');
for(var i = 1; i <= 5; i++)
{
  var item = root.ele('data');
  item.att('x', i);
  item.att('y', i * i);
}

<squares>
  <data x="1" y="1"/>
  <data x="2" y="4"/>
  <data x="3" y="9"/>
  <data x="4" y="16"/>
  <data x="5" y="25"/>
</squares>