JSFiddle - React, Tailwind, and code Playground

HTML

<h1>Use unselectable</h1>
<div>
Outside of unselectable
<div unselectable="on" style="width: 200px; height: 50px; border: 1px solid red;">Some unselectable text
<div style="width: 200px; height: 50px; border: 1px solid black;">This div has no "unselectable"</div>
Some other unselectable text
</div>
Outside of unselectable    
</div>

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<h1>Use onselectstart event</h1>
<div>
Outside of unselectable
<div onselectstart="return false;" style="width: 200px; height: 50px; border: 1px solid red;">Some unselectable text
<div style="width: 200px; height: 50px; border: 1px solid black;">This div has no "unselectable"</div>
Some other unselectable text
</div>
Outside of unselectable    
</div>