[javascript] Bootstrap onClick button event

This seems a silly question but just got bootstrap and it doesn't gives any examples on the website about adding a Javascript callback to a button...

Tried setting my button an id flag and then

<div class="btn-group">
  <button id="rectButton" class="btn">Rectangle</button>
  <button class="btn">Circle</button>
  <button class="btn">Triangle</button>
  <button class="btn">Line</button>
  <button class="btn">Curve</button>
  <button class="btn">Pic</button>
  <button class="btn">Text</button>
  <button class="btn">Gradient</button>
</div>

I want to add a callback to Rectangle button...

$('#rectButton').on('show', function (e) {
    //ACTION
})

cant get the point of bootstrap callbacks.

All I could found on the web is oriented to Rails + Bootstrap... no bootstrap and JS only.

If, like me, you had dynamically created buttons on your page, the

$("#your-bs-button's-id").on("click", function(event) {
                       or
$(".your-bs-button's-class").on("click", function(event) {

methods won't work because they only work on current elements (not future elements). Instead you need to reference a parent item that existed at the initial loading of the web page.

$(document).on("click", "#your-bs-button's-id", function(event) {
                       or more generally
$("#pre-existing-element-id").on("click", ".your-bs-button's-class", function(event) {

There are many other references to this issue on stack overflow here and here.