Poor-man's printf

printf.js

// Named replacements!
const formatString = (string, substitutions = {}) =>
  string.replace(
    /%{([^}]+)}/g,
    (match, id) => {
      return substitutions.hasOwnProperty(id) ? substitutions[id] : match
    }
  );

formatString('%{noun} is %{adjective}', {
  noun: 'my dad',
  adjective: 'the best'
}); // Prints "my dad is the best"

// https://stackoverflow.com/a/4673436
const formatString = (string, ...args) =>
  string.replace(
    /{(\d+)}/g,
    (match, number) =>
      typeof args[number] !== 'undefined' ? args[number] : match
  )

// Even poorer (adapted from: https://github.com/mjackson/expect/blob/ef4aa90/modules/assert.js#L3)
const formatString = (string, args) => string.replace(
  /%s/g,
  (match, number) => typeof args[number] !== 'undefined' ? args[number] : match
);

// GET RICH QUICK!!! https://github.com/alexei/sprintf.js