I want to have different CSS properties depending on the value passed to the component prop. How to achieve this in a <style> tag that's internal on the component file? The component is .astro
#How to use JavaScript inside internal <style> as I would do with JSX?
grave garden
hexed canopyBOT
Hi @grave garden. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave:
In Astro, you can use JavaScript inside the <style> tag by using the define:vars directive. This allows you to define variables within your component's frontmatter script and then use them as CSS variables in your style tag.
Here's an example:
---
const foregroundColor = "rgb(221 243 228)";
const backgroundColor = "rgb(24 121 78)";
---
<style define:vars={{ foregroundColor, backgroundColor }}>
h1 {
background-color: var(--backgroundColor);
color: var(--foregroundColor);
}
</style>
<h1>Hello</h1>
In this example, foregroundColor and backgroundColor are defined in the frontmatter script and then used as CSS variables in the <style> tag. The define:vars directive is used to make these variables available in the <style> tag.
You can find more information about this in the Astro documentation (https://docs.astro.build/en/guides/styling/#css-variables).
Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:
grave garden
@hexed canopy how to use ternary operation to define the value of a property in this case?
hexed canopyBOT
Let me check the knowledge base for you. One moment! :books:
You can use a ternary operation in the frontmatter script to conditionally set the value of a variable. Here's an example:
---
let isDarkMode = true; // This could be a prop
const foregroundColor = isDarkMode ? "rgb(221 243 228)" : "rgb(0 0 0)";
const backgroundColor = isDarkMode ? "rgb(24 121 78)" : "rgb(255 255 255)";
---
<style define:vars={{ foregroundColor, backgroundColor }}>
h1 {
background-color: var(--backgroundColor);
color: var(--foregroundColor);
}
</style>
<h1>Hello</h1>
In this example, isDarkMode is used to conditionally set the values of foregroundColor and backgroundColor. If isDarkMode is true, the colors are set to certain values, otherwise, they are set to different values. These variables are then used in the <style> tag as before.
You can find more information about this in the Astro documentation (https://docs.astro.build/en/guides/styling/#css-variables).
Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:
grave garden
@hexed canopy so it's not possible to do it directly on the <style> ?
hexed canopyBOT
Let me check the knowledge base for you. One moment! :books:
No, it's not possible to use JavaScript directly within the <style> tag in Astro. The <style> tag in Astro only supports CSS. However, you can use JavaScript in the frontmatter script to define variables, and then use those variables in your <style> tag with the define:vars directive, as shown in the previous examples.