title: Can I target a specific Flexbox container and fill it with the contents of another file?
body: <p>I am looking for a way to dynamically populate a submenu depending on the selection of the main menu, then, when a user clicks on an item in the submenu, it populates two flexboxes with the contents of another file. I can't figure out how to target a flexbox using JS; or, if that's not possible, what I could do instead. For example:</p>
  <pre><code>    MENU 1     MENU 2     MENU 3     // user selects menu 2, which populates the submenu from a file
                   ^
      submenu 1 submenu 2 submenu 3    // user selects submenu 3, which populates the flexbox containers
  </code></pre>
  <p>FLEXBOX CONTAINERS:</p>
  <pre><code>------------------------  -----------------------------------------
  | SUBMENU 3 HTML PAGE  |  |        SUBMENU 3 HTML PAGE            |
  |                      |  |                                       |
  |                      |  |                                       |
  |   has options that   |  |       dynamically populates           |
  |  affect the contents |  |      based on the options selected    |
  |   of the other box   |  |       in the other box                |
  |                      |  |                                       |
  ------------------------  -----------------------------------------
  </code></pre>
  <p>Is this possible? What should I search to figure it out? I have Googled to no avail, I'm not searching for the right phrase. What should I be looking for?</p>