We want to build HTMLElements and get reference to some of them in an object named controller. Here we say we want reference to elements with an 'id'.<br>
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We test two different methods :<br>
- Create elements from HTML string using DOMParser and use querySelectorAll to build controller<br>
- Create elements from createElement method and build controller from them<br>
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Here we also put the generated DOM in a fragment because we want to be able to append generated DOM to any element
