<!DOCTYPE html>

<html>

<head>

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>

<script>

$(document).ready(function () {

$("#btn1").click(function () {

$("#test1").text(function (i, originalText) {

return `Old text: ${originalText} New text: Hello World! (index: ${i})`;

});

});

$("#btn2").click(function () {

$("#test2").html(function (i, originalText) {

return `Old html: ${originalText} New html: Hello <b> World! </b> (index: ${i})`

});

});

$("#btn3").click(function () {

$("#test3").val("Hello World!");

});

$("#btn4").click(function () {

$("#hreftag").attr({

"href": "https://github.com/"

});

$("#linktag").children("a").text("github.com");

});

});

</script>

</head>

<body>

<p id="test1">This is a <b>bold</b> paragraph.</p>

<p id="test2">This is another <b>bold</b> paragraph.</p>

<p>Input field: <input type="text" id="test3" value="Mickey Mouse"></p>

<p id="linktag"><a id="hreftag" href="https://www.google.com/" target="blank">google.com</a></p>

<button id="btn1">Show Old/New Text</button>

<button id="btn2">Show Old/New HTML</button>

<button id="btn3">Set Value</button>

<button id="btn4">Change href and title</button>

</body>

</html>