@emotion/cache

What is @emotion/cache?

The @emotion/cache package is part of the Emotion library, a powerful tool for writing css styles with JavaScript. It is specifically designed to create custom instances of Emotion's cache, which can be useful for configuring how styles are processed, inserted, and optimized. This can be particularly beneficial in environments with specific styling needs or when integrating with complex applications.

What are @emotion/cache's main functionalities?

Custom Cache Creation

This feature allows the creation of a custom cache with a specified key prefix. This is useful for isolating styles in large applications or when using multiple emotion instances on the same page.

import createCache from '@emotion/cache';

const myCache = createCache({ key: 'my-prefix' });

Configuring Cache Options

This feature enables the configuration of the cache with specific options like stylis plugins and whether to prepend the styles. It allows for fine-tuning how styles are processed and inserted into the DOM.

import createCache from '@emotion/cache';

const myCache = createCache({
  key: 'custom',
  stylisPlugins: [],
  prepend: true
});

Other packages similar to @emotion/cache

styled-components

Styled-components is another CSS-in-JS library that allows you to use tagged template literals to style your components. It creates scoped styles without the need for manual cache management, which differs from @emotion/cache where you can configure and manage your own cache.

jss

JSS (JavaScript Style Sheets) is a CSS-in-JS library that allows for similar customization and optimization of style sheets. JSS provides a more extensive API for managing rules and stylesheets programmatically, which can be seen as more flexible compared to the focused cache management approach of @emotion/cache.

README

@emotion/cache

createCache

createCache allows for low level customization of how styles get inserted by emotion. It's intended to be used with the <CacheProvider/> component to override the default cache, which is created with sensible defaults for most applications.

import createCache from '@emotion/cache'

export const myCache = createCache({
  key: 'my-prefix-key',
  stylisPlugins: [
    /* your plugins here */
  ]
})

Primary use cases

• Using emotion in embedded contexts such as an <iframe/>

• Setting a nonce on any <style/> tag emotion creates for security purposes

• Using emotion with a developer defined <style/> tag

• Using emotion with custom Stylis plugins

Options

nonce

string

A nonce that will be set on each style tag that emotion inserts for Content Security Policies.

stylisPlugins

Function | Array<Function>

A Stylis plugin or plugins that will be run by Stylis during preprocessing. Read the Stylis docs to find out more. This can be used for many purposes such as RTL.

prefix

boolean | Function, defaults to true

Allows changing Stylis's vendor prefixing settings. It can be a boolean or a function to dynamically set which properties are prefixed. More information can be found in the Stylis docs.

key

string, defaults to "css"

The prefix before class names. It will also be set as the value of the data-emotion attribute on the style tags that emotion inserts and it's used in the attribute name that marks style elements in renderStylesToString and renderStylesToNodeStream. This is required if using multiple emotion caches in the same app.

container

HTMLElement

A DOM node that emotion will insert all of its style tags into. This is useful for inserting styles into iframes.