JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" name="lastNameSend" id="lastNameSend" placeholder="email" class="sendFormInput"></input>
<input id="sendPhysButton" class="button button_at_left" type="submit">

JavaScript

$(document).on("click","#sendPhysButton", function(event){
	alert($("#lastNameSend").val().search(/^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$/));
	event.preventDefault();
});