JSFiddle - React, Tailwind, and code Playground

HTML

<input id="subscribe-email" type="email" required="required" placeholder="john.doe@example.com" />
            
<button type="submit" id="subscribe-submit" onClick="check()">
click me
</button>

JavaScript

function check()
{
    if(!document.getElementById("subscribe-email").checkValidity())
      {
        //do your stuff here  
        alert("input not valid!");
      }else
      {
          callMeIfValid();
      }
}

function callMeIfValid()
{
    //submit form or whatever
    alert("valid input");
}