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• JavaScript
• HTML
• CSS
• Result

$(function() {
    //many 
    $("#output1").html("length is: " + $("li").length);
   // one
   $("#output2").html("length is: " + $("ul").length);
   // one of many
   $("li").each( function(i,o) { 
          $("#output3").html("length is: " + o.length);
      });  
});
  

<ul>
    <li>list 1</li>
    <li>list 2</li>
    <li>list 3</li>
</ul>

<div id="output1"></div>
<div id="output2"></div>
<div id="output3"></div>