JSFiddle - React, Tailwind, and code Playground

HTML

<form name="formName" method="post" action="#">
<input type="text" name="attendant[email]" size="13" value="">  
<input type="text" name="attendant[email]" size="13" value="">
<input type="text" name="attendant[email2]" size="13" value="">
<input type="text" name="attendant[email2]" size="13" value="">
<input type="submit" name="submit"> 
</form>

JavaScript

$("form").submit(function(event) {
    if ($("input:text[name='attendant\\[\email\]']", this).filter(function() {
            return $.trim(this.value) == "";
        }).length) {
        window.alert("No member email1 should be empty.");
            
        event.preventDefault();
    }
       else if ($("input:text[name='attendant\\[\email2\]']", this).filter(function() {
            return $.trim(this.value) == "";
        }).length) {
        window.alert("No member email2 should be empty.");
           
        event.preventDefault();
    }
});