Example using tagged templates

tagged-template.js

var guy = 'Paul';
var age = 96;

function myTag(strings, personExp, ageExp) {
  var str0 = strings[0]; // "That "
  var str1 = strings[1]; // " is a "

  var ageStr;
  if (ageExp > 99){
    ageStr = 'centenarian';
  } else {
    ageStr = 'youngster';
  }

  // You can even return a string built using a template literal - just to be fancy
  return `${str0}${personExp}${str1}${ageStr}`;
}

var output = myTag`That ${ guy } is a ${ age }`;

console.log(output);
// prints: That Paul is a youngster

var lady = 'Elizabeth';
var age = 107;

var output = myTag`That ${ lady } is a ${ age }`;

console.log(output);
// prints: That Elizabeth is a centenarian