how to read select option value in javascript 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: use js to get select value

// reference to 'scripts' select list 
// used throughout the examples below
var sel = document.getElementById('scripts');

// display value property of select list (from selected option)
console.log( sel.value );