how to show dropdown selected value in html code example

Example 1: javascript get selected option

var e = document.getElementById("selectElementID");
var value=e.selectElement.options[e.selectedIndex].value;// get selected option value
var text=e.options[e.selectedIndex].text;//get the selected option text

Example 2: selected dropdown value

Plain JavaScript:
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var e = document.getElementById("elementId");
var value = e.options[e.selectedIndex].value;
var text = e.options[e.selectedIndex].text;
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jQuery:
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$("#elementId :selected").text(); // The text content of the selected option
$("#elementId :selected").val(); // The value of the selected option