Replace named tokens in a string.

tokens.js

var input = 'Hello, :name.first :name.last! :greeting';

function tokenReplace(str, values) {
  return str.replace(/:([\w.]+)/g, function (token, name) {
    return name.split('.').reduce(function (value, part) {
      return value[part] || null;
    }, values) || token;
  });
}

console.log(tokenReplace(input, {
  name: {
    first: 'Brian',
    last: 'Link'
  },
  greeting: 'How are you doing?'
}));

// Should output: "Hello, Brian Link! How are you doing?"