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                <select id="select">
	<option disabled selected>Select an Option</option>
<a target="_parent" href="#" id="go-link">Go!</a>




                // wrap expressions in IIFE statement
(() => {
	// declare script variables that are IIFE protected
	let modifiedHref = "";
	let selectElement = document.getElementById("select");
	// IIFE completion will discard these variables until invoked again

	// set the modifiedHref variable value depending on the selection chosen.
	function setModifiedHref() {
		switch ( // "event target value is '' from event listener.
		) {
			// cases reflect the selected options from select element.
			case "Google":
				modifiedHref = "";
			case "Apple":
				modifiedHref = "";
			// set default case. I haven't had it fire yet. I'm using it for error catching. That's probably wrong.
				console.log("Something went wrong.");

	// set the href of the "Go!" link to current value of modifiedHref when called.
	function setGoLinkHref() {
		document.getElementById("go-link").setAttribute("href", modifiedHref);

	selectElement.addEventListener("change", (event) => {

// try to access the variable after the IIFE finishes.
// this will return "undefined" on purpose. Try it yourself!
// the "global" variables to this script will not polute global variables in other scripts on the page.