jQuery/JS: single click event

single-click-event.js

// jQuery
$( "#button" ).one( "click", function() {
  alert( "Test" );
});

// JS
var btn = document.getElementById( "button" ),
    count = 0;

btn.addEventListener( "click", function() {
  count++;
  if( count == 1 ) {
    alert( "Test" );
  }
  
}, false);