JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<form>
<input type="text" placeholder="zip field" id="formFieldZip"/>  
<input type="text" placeholder="other form field"/>
</form>

JavaScript

window.onload = function() {
	let inLA = false;
	var zipsLA = ["700, 701, 703, 704, 705, 706, 707, 708, 710, 711, 712, 713, 714"];
	const $zipField = document.getElementById('formFieldZip')
	const $zipValue = document.getElementById('formFieldZip').value

  $zipField.addEventListener('blur', function(){
		console.log(zipValue);
	});
};