Are there variables in html

The beauty of CSS variables is their reactive nature. As soon as they are updated, whatever property has the value of the CSS variable gets updated as well. For this simple example, the background and color of the text of the entire page is based off of CSS variables.

When you click any of the buttons above, they set the CSS variable to some other color. As a result of that, the background of the page is updated. CSS variables will take effect even if they are set inline. With JavaScript, we get a hold of the root document, and we set the new value for the CSS variable inline.

The markup consists of three buttons within a. To keep things short I have truncated the content within the article element. Within this article element is the content of the page. Instead of just setting the background-color and color of the page in stone, we will set them based on variables.

The reason for this is kind of obvious. Whenever a button is clicked, we will change the value of both variables within the document. The root element here is the HTML element. Iterate over each of the buttons and add an event listener to them, upon click. Every button being clicked will have the handleThemeUpdate as its callback function. It becomes important to note what button was clicked and then perform the right operation.

In the light of that, a switch operator is used, and some operations are carried out based on the value of the button being clicked. Go ahead and take a second look at the block of JavaScript code. Remember that the color of the boxes are dynamically updated, and that the box container is rotated in 3d space as the range input is changed. You can go ahead and play with it on Codepen. This is a superb example of updating CSS variables with JavaScript and the reactivity that comes with it.

I hope you can read through and understand it. If not, drop a comment or tweet. The other bit after the forward slash represents the background-size This has been set to px If you made this smaller, the image would be smaller too. It prevents the background from repeating itself. Finally, anything that comes after the comma is a second background declaration. The primary color there is the sunrise yellow color.

No big deal. The main container acts as a flex container and rightly positions the direct child in the center of the page. This happens to be our beloved color-box container. The transform shorthand applies two different functions. One, the perspective, and the other, the rotation along the Y axis. The perspective function is applied to an element that is being transformed in 3D space.

It activates the three dimensional space and gives the element depth along the z-axis. You can read more about the perspective function on codrops. Upon activation the 3d space, the element has the planes x, y, z. The rotateY function rotates the element along the Y plane. The following diagram from codrops is really helpful for visualizing this. When you move the slider, do you know what function affects the rotation of the.

Since the value passed into the rotateY function will be updated via JavaScript, the value is represented with a variable. As a general rule of thumb, and for explicit freedom, it is advised that when building single tokens, you store values in your variables without units.

You can convert them to any unit you want by doing a multiplication via the calc function. The value of this variable can be updated in JavaScript as much as we like.

We know we will be updating the background color of each box. We also know that this background color has to be represented by a variable so it is accessible via JavaScript. If a variable used within a property value is invalid, the property will take on its initial value. Consequently, when --bg-1 is invalid or NOT available, the background will default to its initial value of transparent.

Set up an event listener for when the value of the range input changes, range. So, let me fix my mess. So, can you use CSS variables in production today? Be sure to check what the adoption rate is for yourself, though. On the bright side, you can use a preprocessor like Myth.

How cool, huh? Get the Ebook for offline reading, and also get a private slack invite where you can ask me anything. If this article was helpful, tweet it. Learn to code for free. Get started. Forum Donate. Emmanuel Ohans. This is the final project. The color of the boxes are dynamically updated Notice how the colors of the boxes are dynamically updated, and how the box container is rotated in 3D space as the range input is changed.

This is going to be fun! Reason 1: More readable code Without saying much, you can quickly tell how readable and more maintainable variables make any code base. It becomes super-easy. They provide the ability to assign values to a CSS property with a customized name. Variables follow the standard cascading rules, so it is possible to define the same property at different specificity levels.

Join today and get access to 1,'s of books and videos. Sign up today! This post will explain how to use CSS Variables and some practical applications. Let's start! Declaring a Variable Variables can have global or local scope. Iste doloribus dolorum eaque veritatis quia quod? Libero, dolorem.

Reprehenderit mollitia quos quia qui. Nisi dolor reprehenderit, ad sunt aperiam officiis! How are we doing?

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