set selected option javascript by value 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: make select option selected javascript

document.getElementById('personlist').getElementsByTagName('option')[11].selected = 'selected'