How to simplify javascript event listeners? -


what want achieve is, when hovering on li id="a", corresponding ul id="aa" appears. have html code:

<ul>   <li id="1">option1</li>   <li id="2">option2</li> </ul> <ul id="11">   <li>option1.1</li>   <li>option1.2</li> </ul> <ul id="22">   <li>option2.1</li>   <li>option2.2</li> </ul>

and javascript code:

for (i=1; i<3; i++) {   var fn = (function(i) {     var li = document.getelementbyid(i);     var ul = document.getelementbyid("" + + i);     li.addeventlistener("mouseover", function() {       ul.style.opacity = "1";     }, false);   })(i); }

and works expected, here user jordan gray stated possible rid of loop , instead create 1 event listener list items - achieve here. unfortunately not understand code , thankful if explain me or suggest solution.

here how can use logic in code:

var ul = document.getelementbyid('ul-id');    ul.addeventlistener('mouseover', function(e) {        if (e.target.nodename.touppercase() !== "li") return;    document.getelementbyid("" + e.target.id + e.target.id).style.opacity = "0.6";  });
<ul id="ul-id">    <li id="1">option1</li>    <li id="2">option2</li>  </ul>  <ul id="11">    <li>option1.1</li>    <li>option1.2</li>  </ul>  <ul id="22">    <li>option2.1</li>    <li>option2.2</li>  </ul>


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