JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://unpkg.com/vue"></script>
<div id="app">
  <input id="coupon" type="text" name="coupon" v-model="coupon" value="default value" />
</div>

JavaScript

new Vue({
	el: '#app',
	data: {
    coupon: '',
		// coupon: $('#coupon').val(),
	}
});