title: i18next-react and custom format
body: <p>I do use i18next-react and try to work with formating.
  So I've setup in my init formating like that:</p>
  <pre class="lang-js prettyprint-override"><code>i18n.use(initReactI18next).init(
    {
      ...
      interpolation: {
        escapeValue: false,
        // eslint-disable-next-line no-unused-vars
        format: function (value, format, lng) {
          if (format === 'uppercase') return value.toUpperCase();
          if (format === 'lowercase') return value.toLowerCase();
          if (format === 'capitalize') return `${value.substr(0, 1).toUpperCase()}${value.substr(1)}`;
          return value;
        },
      },
      ...
    },
  </code></pre>
  <p>If I do in my react-component this:</p>
  <pre><code>import i18next from 'i18next';
  i18next.format('edit', 'capitalize'),
  </code></pre>
  <p>It works like expected... the word edit becomes capital lettered.</p>
  <p>BUT, how do I use it with my own translation: <code>t('edit')</code>
  I wonder if there is a way to call the formating with react-i18next instead of i18next package</p>
  <p>If I try with: <code>t('{{edit, capitalize}}'),</code>, I got this error:
  <a href="https://i.stack.imgur.com/ti3MY.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ti3MY.png" alt="enter image description here" /></a></p>
  <p>What I try is at least to decide in my t()-MEthod to use a given format on this string.</p>