How to implement such output of phone number JS,ModX?

Question

JavaScript

Hello!
How to implement such an output on click to display a phone number?
Placeholder not as I can not withdraw.

let tel = '';
  $('.tel span').text('+7 9XX XXX XX XX').attr('title','Показать номер телефона').on('click',function(){
      $(this).html(tel);
  });

Answer 1

For example. Set the span ID to "Show phone number" and the block where the TV is located.

document.getElementById("show_phone").onclick = function() {show()};
function show() {
  document.getElementById("phone").style.display="block";
}