title: join arrays of object and create new array
body: <p>I have an array of object like this:</p>
  <pre><code> example = [
    {
      id: 1,
      child: [
        {
          id: 1,
          name: &quot;child 1&quot;,
        },
      ],
    },
    {
      id: 2,
      child: [
        {
          id: 2,
          name: &quot;child 2&quot;,
        },
        {
          id: 3,
          name: &quot;child 3&quot;,
        },
      ],
    },
  ];
  </code></pre>
  <p>and I want to get an array of child objects like this:</p>
  <pre><code>[{...},{...},{...}]
  </code></pre>
  <p>I tired to loop through with map but I'm getting an array of two object.</p>