In jQuery, the toggle() function is used to hide and show elements.

Here's an example of how to use it:

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// HTML
<button>Toggle Element</button>
<p>Hello, I will be toggled!</p>

// JavaScript/jQuery
$("button").on("click", function() {
  $("p").toggle();
});

In this example, clicking the button will toggle the visibility of the <p> element. If it's hidden, it will be shown. If it's shown, it will be hidden.

To toggle a div on click of an HTML element, you can use JavaScript with a combination of HTML and CSS. Here's an example:

HTML:

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<div class="toggle-div">
  <p>Click on this text to toggle the div</p>
  <input type="checkbox" id="toggle" />
  <div class="content">
    This is the div you want to toggle
  </div>
</div>

CSS:

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.content {
  display: none;
}

JavaScript:

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const toggle = document.getElementById("toggle");
const content = document.querySelector(".content");

toggle.addEventListener("click", function() {
  if (toggle.checked) {
    content.style.display = "block";
  } else {
    content.style.display = "none";
  }
});

In this example, we're listening to the click event on the input element with the id of toggle. When the input element is checked, we display the div with the class of content. When it's unchecked, we hide the div again. The content div itself has a default style of display: none to start with, which means it's hidden until the input element is clicked.

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<button id="like-btn" onclick="toggleLike()">Like</button>
<span id="like-count"></span>

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{
  "likes": 0
}

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let data = {
  "likes": 0
}

function toggleLike() {
  let likeBtn = document.getElementById("like-btn");
  let likeCount = document.getElementById("like-count");

  if (likeBtn.innerHTML == "Like") {
    likeBtn.innerHTML = "Dislike";
    data.likes++;
    likeCount.innerHTML = data.likes + " like(s)";
  } else {
    likeBtn.innerHTML = "Like";
    data.likes--;
    likeCount.innerHTML = data.likes + " like(s)";
  }
}

To keep a button selected after it is clicked, you can toggle a CSS class on the button using JavaScript. Here's an example code snippet in JavaScript that demonstrates how to achieve this:

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const button = document.querySelector('#myButton'); // select the button element
button.addEventListener('click', function() {
  button.classList.toggle('selected'); // toggle the 'selected' class on click
});

In the CSS, you can define the 'selected' class to change the appearance of the button to indicate it has been selected:

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.selected {
  background-color: blue;
  color: white;
  /* add any other styling you want for a selected button */
}

Here, the background color of the button will change to blue and the text will change to white once the button is clicked. You can customize the CSS class to your liking.

To change the name of a class of an element using document.querySelector, you can use the classList property of the selected element which provides several methods to add, remove or toggle classes. Here's an example in JavaScript:

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// select the element to change its class name
const myElement = document.querySelector('#my-element');

// use the classList property to modify the class names
myElement.classList.remove('old-class-name');
myElement.classList.add('new-class-name');

In this example, querySelector is used to select an element with an id of my-element. The classList property is then used to remove the class old-class-name and add the class new-class-name.

You can check out more information about the classList property on the MDN web docs: https://developer.mozilla.org/en-US/docs/Web/API/Element/classList

You can change the class of an HTML element using JavaScript Selectors. To change an element's class, use the classList method. The .toggle() method can be used to add or remove a class from an element:

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document.querySelector("#element").classList.toggle("classname");

This statement will add the specified class to the element if it does not already have the class, or remove it if the element already had the class.

You can also use the .add() and .remove() methods to add or remove a single class from an element, respectively:

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document.querySelector("#element").classList.add("classname");
document.querySelector("#element").classList.remove("classname");

For more information, see MDN's documentation on classList.