Handlebars:
Template
{{>header}}
<hr/>
{{#each persons}}
{{>person person=.}}
{{/each}}
header
[rename] [delete]
{{persons.length}} persons found
person
[rename] [delete]
The person {{loud person.name}} is {{person.age}} years old.
Preparation-Script
Handlebars.registerHelper('loud', function (aString) {
    return aString.toUpperCase()
})
Input
{
  persons: [
    { name: "Nils", age: 20 },
    { name: "Teddy", age: 10 },
    { name: "Nelson", age: 40 },
  ],
}
Output
3 persons found
<hr/>
The person NILS is 20 years old.
The person TEDDY is 10 years old.
The person NELSON is 40 years old.