I created a button used DOM how do I get an on click for it code example

Example 1: javascript onclick

document.getElementById("myBtn").addEventListener("click", function() {
  alert("Hello World!");
});

Example 2: javascript click event

// EXAMPLE: 
document.querySelector(`.check`).addEventListener(`click`, 
   function () {
      console.log(document.querySelector(`.guess`).value;
   }
);

// SYNTAX:
//  .addEventListener(`click`, 
//     function () {
//       
//     }
//  );