var firstName = 'Tal';
var screenName = 'ketacode'

// Ugly
'Hi, my name is ' + firstName + ' and my twitter screen name is @' + screenName;

// Super
var template = 'Hi, my name is {first-name} and my twitter screen name is @{screen-name}';
var txt = template.replace('{first-name}', firstName)
                  .replace('{screen-name}', screenName);