Let's say you have a paragraph.

<pid="target">rainbow 🌈</p>

And you need to change it's color with JS. What options do you have?

1. Inline styles

The most straightforward path. Query the element from DOM and change it's inline styles.

document.getElementById('target').style.color='tomato';

Short and simple.

2. Global styles

Another option is to create<style> tag, fill it with CSS rules and append the tag to the DOM.

varstyle=document.createElement('style');style.innerHTML=`  #target {  color: blueviolet;  }  `;document.head.appendChild(style);

3. CSSOM insertRule

Third option is less known. We gonna useCSSStyleSheetinsertRule method.

varstyle=document.createElement('style');document.head.appendChild(style);style.sheet.insertRule('#target {color: darkseagreen}');

While it might look similar to the 2nd option, it's definitely different.

As you can see in Chrome devtools,<style> tag is empty, but the style (darkseagreen color) is applied to the element. Also the color can't be changed via devtools because Chrome doesn't allowediting dynamic CSS styles.

Actually such behavior was the motivation to write this post. A popular CSS-in-JS libraryStyled Components use this feature to inject styles in production mode because of performance. This feature might be undesirable in specific projects or environments and some folks complain about it in the project's issues.

4. Constructable Stylesheets (July 2019 update)

It's now possible to createCSSStyleSheet object from JavaScript.

// Create our shared stylesheet:constsheet=newCSSStyleSheet();sheet.replaceSync('#target {color: darkseagreen}');// Apply the stylesheet to a document:document.adoptedStyleSheets=[sheet];

More details arehere.
This option is only valid for Chrome, so use with caution.

Do you know other options to add styles with javascript? What is your preferred option these days?

Thanks for reading!