This is a validation formula or method condition to validate an email string from an input or text field with JavaScript. (No RegEx, just pure JavaScript)

emailCheck.js

//Save the value of the field into a variable
var emailValue = emailField.getValue();

/* This formula or method condition in five easy steps
 * 
 * 1- First searches for an "@" in the string
 * 2- Then it checks for more than one "@"
 * 3- Then checks if the subdomain area is less than 4 characters
 * 4- Then checks if the position of the last "." is less than 3 spaces after the "@"
 * 5- Then checks if there are two or less characters after the last "."
 */

if ( ( emailValue.search("@") == -1 )  || ( emailValue.indexOf("@") !== emailValue.lastIndexOf("@") ) || emailValue.indexOf("@") < 4 || emailValue.lastIndexOf(".") < emailValue.indexOf("@") + 3 || emailValue.lastIndexOf(".") + 2 >= emailValue.length )
{
    
    alert("Please enter a valid email");
  
};
  

@j-acevedo ,

This is the email format validation formula or method condition that you're looking for...