Following along

Remember to “git pull” on teacher repository to update to lates.

Run this notebook in VSCode
Activate Help-Toogel Developer Tools to add console outputs to runtime experience

Referencing HTML elements using javascript

To get an HTML element, use document.getElementById("idTag")
You will use the ID that you set in your HTML
if you console.log the resulting variable you will get some information about the element

%%html
<!-- the ID must be specified within the element -->
<h1 id="domTitleID">My Title</h1>

<!-- javascript goes here -->
<script>
var titleElement = document.getElementById("domTitleID")
<!-- outputs h1 tag -->
console.log("Example #1, show element in DOM")
console.log(titleElement)
</script>

Getting the data within the HTML element

The variable titleElement stores the “object”
Basically think of this as the group of data enclosed in HTML tag
To access a certain type of data from an “object” we use “.” notation
- .innerHTML gets data within center of tag

%%html
<!-- the ID must be specified within the element -->
<h1 id="domTitleIDget">My Title</h1>

<!-- javascript goes here -->
<script>
var titleElement = document.getElementById("domTitleIDget")
<!-- outputs h1 innerHTML from h1 tag -->
console.log("Example #2, show innerHTML")
console.log(titleElement.innerHTML)
</script>

Setting the data within the HTML Element

The innerHTML data in this “object” can be set like a variable
- Change the value of the innerHTML using the “=” (assignment) operator

%%html
<!-- the ID must be specified on the element -->
<h1 id="domTitleIDset">My Title</h1>

<!-- javascript goes here -->
<script>
var titleElement = document.getElementById("domTitleIDset")
titleElement.innerHTML = "Set and Update My Title"
<!-- outputs h1 innerHTML after h1 tag has been updated -->
console.log("Example #3, update innerHTML")
console.log(titleElement.innerHTML)
</script>

Creating elements

Create a new element with the document.createElement function -> takes in the type of element
Set properties in the element just like the “h1” example

%%html
<!-- the ID must be specified on the element -->
<div id="divContainerID">
    <h1 id="h1ElementID">My Title</h1>
</div>

<!-- javascript goes here -->
<script>
   // creates a new element
   var pElement = document.createElement("p")
   pElement.innerHTML = "Starting a paragraph of text."
   
   // outputs p tag after it has been created
   console.log("Example #4, create a p tag within JS")
   console.log(pElement)
</script>

Issue! How to Create element that appears in HTML?

Here is a visualization of what is happening => the “p” is not placed inside the HRML page!

Solution

Correct by placeing the element somewhere in the page
For example, we could add the element within the div
- For this, use the appendChild function on the div object (the parameter would be the p element we created)
- Remember, use the getELementById to get the object for something in the html (the div!)
Updated Diagram

%%html
<!-- the ID must be specified on the element -->
<div id="divContainerIDset">
    <h1 id="h1ElementIDset">My Title</h1>
</div>

<!-- javascript goes here -->
<script>
   // creates a new element
   var pElement = document.createElement("p")
   pElement.innerHTML = "Starting a paragraph of text."
   
   // outputs p tag after it has been created
   console.log("Example #5, add p tag to HTML")
   console.log(pElement)
   
   // place the p element inside the HTML page
   var div = document.getElementById("divContainerIDset")
   div.appendChild(pElement)
</script>

Functions in JavaScript, using with DOM

Functions allow you to “do something”
- ex. “eat food” in a Snake Game
Functions were used in previous examples
- console.log = “print something”
- document.getElementById = “find an element with id”
Functions take in parameters, what to do (inside the parenthesis)
- the parameter tells console.log what to print
- the parameter in document.getElementById tells the id of the element
Functions can be used with DOM as well, thes will be shown below

Creeating functions

document functions functions were used to create a lot of functionality, but how can a developer create their own?
function are useful to avoid writing the same code over and over again
function can contain parameters for input (they effectively become variables)
function can contain a return, the are the “output” of the function

%%html
<!-- the ID must be specified on the element -->
<div id="divContainerIDfunction">
    <h1 id="h1ElementIDfunction">My Title</h1>
</div>

<!-- javascript goew here -->
<script>
    // define a function => takes parameter text, returns a new p tab
    function createPTag(text) {
        // creates a new element
        var pElement = document.createElement("p")

        // using the parameter like a variable
        pElement.innerHTML = text
        
        // outputs p tag after it has been created
        console.log("Example #6, add p tag using a function")
        console.log(pElement)

        return pElement;
    }

    // using a function to create p tag
    var pTag = createPTag("Starting a paragraph with cooler text than before.")

    // place the p element in the webpage
    var div = document.getElementById("divContainerIDfunction")
    div.appendChild(pTag)
</script>

OnClick Event

Run a function when an event occurs
- In this case, the p tag is created when the button is clicked

%%html
<!-- the ID must be specified on the elements -->
<button id="buttonID">Click here!</button>

<div id="divContainerIDbutton">
    <h1 id="h1ElementIDbutton">My Title</h1>
</div>

<!-- our javascript goe here -->
<script>
    // define a function => takes parameter text, returns a new p tab
    function createPTag(text) {
        // creates a new element
        var pElement = document.createElement("p")

        // using the parameter like a variable
        pElement.innerHTML = text
        
        // outputs p tag after it has been created
        console.log("Example #7.1, add p tag using a function")
        console.log(pElement)

        return pElement;
    }

    // create a function that sets specific text and adds to div
    function addPTagOnButton() {
        // using our new function
        var pTag = createPTag("Starting a paragraph with text created on button press.")

        // place the p element in the webpage
        var div = document.getElementById("divContainerIDbutton")

        // add p tag to the div
        div.appendChild(pTag)
        
        // outputs p tag after it has been created
        console.log("Example #7.2, update container adding a 'p' tag")
        console.log(div)
    }

    // add the P tag when our button is clicked
    var myButton = document.getElementById("buttonID")
    myButton.onclick = addPTagOnButton
    
</script>

Hacks

Copy your HTML code from the HTML hacks. Write a Javascript snippet to switch the links of the two a tags when a button is pressed. Once they are switched, change the inner HTML of the top p tag to the word “switched!”

%%html
<div>
<p id="Valorant">Valorant is a dynamic and strategic first-person shooter developed by Riot Games, known for their massive success with League of Legends. Released in June 2020, Valorant quickly garnered a dedicated player base and established itself as a competitive esports title. Set in a near-futuristic world, the game pits two teams of five players against each other, with one team taking on the role of attackers trying to plant a Spike (a bomb) at designated sites, and the other team as defenders, striving to thwart their plans. What sets Valorant apart from other FPS games is its blend of precise gunplay reminiscent of Counter-Strike with a unique roster of "Agents," each possessing distinct abilities that add layers of strategy and team coordination to the gameplay. The diversity of agents allows for a wide range of playstyles, from stealthy and tactical to aggressive and explosive, ensuring that every player can find their niche. Valorant's competitive scene has flourished with numerous tournaments and leagues worldwide, offering substantial prize pools and attracting top-tier professional players. Riot Games' commitment to regularly updating the game, balancing agents and weapons, and introducing new content keeps the experience fresh and engaging for both casual and competitive players. The game's emphasis on communication, teamwork, and precise aiming skills makes it a thrilling and intellectually stimulating experience, as players constantly adapt and strategize to outmaneuver their opponents. Whether you're a newcomer or a seasoned FPS veteran, Valorant offers an exhilarating and challenging gaming experience that continues to evolve and captivate players around the globe.</p>
<p>Do you feel as if you're not good enough? Do you wish to get better? Do you want to aim better? Get better game sense? Learn how to master your agents? Click the button to begin ranking up!</p>
<button id="SButton">Click Me to Get Better!</button>
</div>
<br>
<br>
<div>
<a id="VTracker" href="https://tracker.gg/valorant">Valorant Tracker</a>
<br>
<a id="ATrainer" href="https://www.3daimtrainer.com/">Aim Trainer</a>
<p>These are websites are beneficial to your progress in Valorant. Click on these websites for more information!</p>




<script>
    function changelink() {
    var link1 = document.getElementById("VTracker");
    link1.setAttribute('href', "https://www.3daimtrainer.com/");
    link1.innerHTML = "Aim Trainer";
    
    var link2 = document.getElementById("ATrainer");
    link2.setAttribute('href', "https://tracker.gg/valorant");
    link2.innerHTML = "Valorant Tracker";
    
    var para = document.getElementById("Valorant");
    para.innerHTML = "Switched!"
    }

    var switchButton = document.getElementById("SButton");
    switchButton.onclick = changelink;
</script>
    

Valorant is a dynamic and strategic first-person shooter developed by Riot Games, known for their massive success with League of Legends. Released in June 2020, Valorant quickly garnered a dedicated player base and established itself as a competitive esports title. Set in a near-futuristic world, the game pits two teams of five players against each other, with one team taking on the role of attackers trying to plant a Spike (a bomb) at designated sites, and the other team as defenders, striving to thwart their plans. What sets Valorant apart from other FPS games is its blend of precise gunplay reminiscent of Counter-Strike with a unique roster of "Agents," each possessing distinct abilities that add layers of strategy and team coordination to the gameplay. The diversity of agents allows for a wide range of playstyles, from stealthy and tactical to aggressive and explosive, ensuring that every player can find their niche. Valorant's competitive scene has flourished with numerous tournaments and leagues worldwide, offering substantial prize pools and attracting top-tier professional players. Riot Games' commitment to regularly updating the game, balancing agents and weapons, and introducing new content keeps the experience fresh and engaging for both casual and competitive players. The game's emphasis on communication, teamwork, and precise aiming skills makes it a thrilling and intellectually stimulating experience, as players constantly adapt and strategize to outmaneuver their opponents. Whether you're a newcomer or a seasoned FPS veteran, Valorant offers an exhilarating and challenging gaming experience that continues to evolve and captivate players around the globe.

Do you feel as if you're not good enough? Do you wish to get better? Do you want to aim better? Get better game sense? Learn how to master your agents? Click the button to begin ranking up!

Valorant Tracker
Aim Trainer

These are websites are beneficial to your progress in Valorant. Click on these websites for more information!

Using Javascript with HTML DOM • 28 min read

Description