unless_blank Handlerbars JS helper

gistfile1.js

// Uses same syntax as #if helper but initially returns false for falsey or empty string values.
Handlebars.registerHelper('unless_blank', function(item, block) {
  return (item && item.replace(/\s/g,"").length) ? block.fn(this) : block.inverse(this);
});

// Only the first 2 rows will be displayed.
data = {
 rows: [
   'user_name': 'Blake',
   'user_name': 'Joe',
   'user_name': '',
   'user_name': '   ',
   'user_name': null
 ]
}

{{#unless_blank user_name}}
  Welcome back, {{user_name}}
{{/unless_blank}}