title: Extend javascript object without jquery
body: <p>I have 2 objects, for example:
  1st: </p>
  
  <pre><code>const langs = {
    en: {
      components: {
        test: 'test'
      },
    },
    de: {
      components: {
        test: 'test'
      },
    },
  };
  </code></pre>
  
  <p>2nd: </p>
  
  <pre><code>const langs2 = {
    en: {
      app: {
        test: 'test'
      },
    },
    pl: {
      app: {
        test: 'test'
      },
    },
  };
  </code></pre>
  
  <p>And now i need to merge these 2 object into one, it should looks like: </p>
  
  <pre><code>{
    en: {
      components: {
        test: 'test'
      },
      app: {
        test: 'test'
      },
    },
    de: {
      components: {
        test: 'test'
      },
    },
    pl: {
      app: {
        test: 'test'
      },
    },
  };
  </code></pre>
  
  <p>There is any solution to do that? I tried Object.assign but when I have 2 same named properties it just override them. So, when I have same lang in 2 object it should extend it, when I have different lang it should just add that to object. I cant use jquery or other lib, so it must be pure js (es6 avaible)</p>