what is addeventlistener in javascript code example

Example 1: javascript onclick event listener

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

Example 2: js addeventlistener

document.getElementById("example").addEventListener('click', function() {
  alert('Click');
});

Example 3: javascript addeventlistener

var element = document.getElementById("#id");
element.addEventListener('click', function(){
	console.log("click");
});

Example 4: javascript addeventlistener

//with jQuery
$("#id / .class").on('click', function(){
	console.log("click");
});

Example 5: addEventListener

<body style="height: 5000px">
 <style>
    body, /* blink currently has bug that requires declaration on `body` */
    html {
      scroll-snap-type: y proximity;
    }
    .snaptarget {
      scroll-snap-align: start;
      position: relative;
      top: 200px;
      height: 200px;
      background-color: green;
    }
 </style>
 <div class="snaptarget"></div>
</body>