title: How do i make a json merger based on non unique keys?
body: <p>I'm working on a react native app with a calendar that use dates as keys in JSON.
  So I want to add to the objects to the JSON file .</p>
  <p>here is the basic JSON file I have</p>
  <pre class="lang-js prettyprint-override"><code>[{&quot;2021-03-22&quot;:[{&quot;name&quot;:&quot;test2&quot;},{&quot;name&quot;:&quot;test2&quot;}],&quot;2021-03-23&quot;:[{&quot;name&quot;:&quot;test3&quot;}]}]
  </code></pre>
  <p>I want to do is to add</p>
  <pre class="lang-js prettyprint-override"><code>{&quot;2021-03-23&quot;:[{&quot;name&quot;:&quot;test4&quot;}]}
  </code></pre>
  <p>and the goal is</p>
  <pre class="lang-js prettyprint-override"><code>[{&quot;2021-03-22&quot;:[{&quot;name&quot;:&quot;test2&quot;},{&quot;name&quot;:&quot;test2&quot;}],&quot;2021-03-23&quot;:[{&quot;name&quot;:&quot;test3&quot;},{&quot;name&quot;:&quot;test4&quot;}]}]
  </code></pre>
  <p>and if I add</p>
  <pre class="lang-js prettyprint-override"><code>{&quot;2021-03-24&quot;:[{&quot;name&quot;:&quot;test4&quot;}]}
  </code></pre>
  <p>it will go</p>
  <pre class="lang-js prettyprint-override"><code>[{&quot;2021-03-22&quot;:[{&quot;name&quot;:&quot;test2&quot;},{&quot;name&quot;:&quot;test2&quot;}],&quot;2021-03-23&quot;:[{&quot;name&quot;:&quot;test3&quot;}],&quot;2021-03-24&quot;:[{&quot;name&quot;:&quot;test4&quot;}]}]
  </code></pre>
  <p>--sry if the code JSON bit wrong but I hope it makes sense.</p>